Stretching 1,000 kilometers (600 miles) from southern Peru into northern Chile, the Atacama Desert is the driest desert in the world. At its center — a bleak, intimidating landscape where rain has never been recorded — the Atacama is the driest place in the world. Here life is nearly absent.
Why so dry? Averaging less than 160 kilometers (100 miles) wide, the desert is flanked on one side by the Pacific Ocean and on the other by the Andes mountains. Air from the west is dry because of cold ocean currents and the Andes block moisture from the East, so the Atacama has few clouds and no rainfall. The land is a series of salt basins and lava flows that support almost no vegetation. The tiny amount of precipitation (less than 1cm /0.4 inches per year) that does fall comes in the form of a marine fog that blows in from the Pacific. The few forms of life found in the Atacama — insects, algae, lichens, a few cacti — survive on moisture from fog and dew.
These extreme dry conditions make the Atacama an ideal place to test Mars rovers and instruments for future Moon and Mars missions. In 2003, scientists duplicated the tests used by the Viking 1 and Viking 2 Mars landers to detect life, and found no signs in Atacama Desert soil. High altitudes, clear air, and absence of light pollution also make the desert an excellent site for astronomical observatories. It’s also a destination for archeologists because the dry air has preserved relics from Pre-Colombian and Paleo-Indian civilizations.
", "thumbnail_image":"", "type_attrs":{}}, "baiji":{"print_name":"Baiji", "sort_name":"baiji", "type":"animal", "definition":"The Baiji is a freshwater dolphin (a small toothed whale) found only in middle and lower reaches of China’s Yangtze River. Grey in color, with a rather long, sharp-toothed beak and very small eyes, Baiji uses echolocation clicks to navigate and find their prey. They live an estimated 24 years, reaching 2.5 meters (8 ft) in length and weighing between 135-230 kilograms (300-510 lbs). As China developed economically in the second half of the 20th century, the Baiji population declined drastically. Pressures include overfishing, industrial pollution, boat collisions, and loss of habitat from dredging and projects like the Three Gorges Dam. Noise pollution from ship traffic on one of the world's busiest waterways interferes with the nearly blind dolphin’s ability to find food and dodge propellers. The Baiji was declared functionally extinct in 2006, making it the first aquatic mammal species to become extinct since the 1950s, when the Japanese Sea Lion and the Caribbean Monk Seal died out.
Fossil records suggest that the Baiji migrated from the Pacific Ocean up the Yangtze River 20 million years ago. It’s one of five freshwater dolphin species; the others survive in the Río de la Plata and Amazon rivers in South America and India’s Ganges and Indus Rivers.
", "thumbnail_image":"", "type_attrs":{"_species":"vexillifer", "_genus":"Lipotes", "_family":"Lipotidae", "_order":"Cetacea", "_class":"Mammalia", "_phylum":"Chordata"}}, "condensation":{"print_name":"condensation", "sort_name":"condensation", "type":"natural_phenomena", "definition":"Condensation is a key component of the water cycle: the endless circulation of water above, on and below Earth’s surface. The opposite of evaporation, condensation is the process by which water vapor in the air changes physical state, turning from a gas into liquid water.
Condensation is crucial to the water cycle because it’s responsible for cloud formation. Clouds form when air containing water vapor rises in the atmosphere, cools, and condenses onto small airborne particles. (Even clear blue skies contain water vapor!) The temperature below which air must be cooled, at constant pressure, in order for water vapor to condense is called the dew point. Clouds are an intricate and critical component of Earth's climate system, and they produce precipitation: the primary way that water returns to Earth’s surface. Deposition, in which ice forms directly from water vapor, is a kind of condensation. Frost and snow are examples of deposition. Sublimation, in which ice changes directly to water vapor, is the opposite of deposition; it’s what causes snow banks to shrink even when the temperature is below freezing.
Condensation trails (contrails) are created when water vapor in airplane exhaust hits the chilly upper atmosphere and condenses to ice or liquid water. Condensation also occurs closer to home, fogging up your glasses when you come inside on a winter day, wetting the outside of your glass of iced tea, or causing ground fog — all examples of what happens when the water vapor in warm air encounters a cooler surface.
", "thumbnail_image":"", "type_attrs":{}}, "dragonfly":{"print_name":"dragonfly", "sort_name":"dragonfly", "type":"animal", "definition":"These impressive insects have large eyes and elongated bodies, and can hover in mid-air on two sets of strong, transparent wings. The earliest dragonflies appeared over 200 million years ago; today there are over 5,000 species. Because their prey typically consists of mosquitoes, midges, and other small insects, dragonflies are valued as predators. They’re usually found near water because their larvae — called "nymphs" — are aquatic creatures. Sensitive to water temperature and quality, dragonfly nymphs may serve as bioindicators of the health of their wetland ecosystems. A number of species are in trouble, primarily a casualty of disappearing or degraded aquatic habitats.
Dragonflies spend almost all of their lives as nymphs, eating other aquatic insects (or even vertebrates like tadpoles and juvenile fish), and going through a series of molts as they grow. In the largest dragonfly species, this stage can last up to five years; in smaller species, between two months and three years. Once fully developed, dragonflies climb out of the water, shed their larval skins, wait for their bodies and wings to expand and harden, and take to the air to eat and to mate.
", "thumbnail_image":"", "type_attrs":{"_order":"Odonata", "_class":"Insecta", "_phylum":"Arthropoda"}}, "kangaroorat":{"print_name":"kangaroo rat", "sort_name":"kangaroo rat", "type":"animal", "definition":"These small rodents are named for the way they hop on their hind feet like tiny kangaroos, using their long, fluffy tails to help balance and steer. Over twenty species are found in arid and semi-arid areas of Canada, the United States and Mexico.
Kangaroo rats are extremely well adapted to their arid habitats. They’re nocturnal. Deep burrows shelter them from the desert heat. They don’t sweat or pant to keep cool, which helps them conserve precious body water. Most remarkably, kangaroo rats never have to drink. This is thanks to their highly water-efficient metabolism. Specialized kidneys (at least four times more efficient than human kidneys at retaining water and excreting salt) produce urine that’s extremely concentrated. So little water is lost that kangaroo rats can extract all the water they need from their diet of seeds, leaves, stems, and insects.
", "thumbnail_image":"", "type_attrs":{"_genus":"Dipodomys", "_family":"Heteromyidae", "_order":"Rodentia", "_class":"Mammalia", "_phylum":"Chordata"}}, "mekongcatfish":{"print_name":"Mekong giant catfish", "sort_name":"mekong giant catfish", "type":"animal", "definition":"The largest freshwater fish in the world, the Mekong catfish is native to the lower half of the Mekong River basin in Cambodia, Laos, Thailand, and Vietnam. This solid gray member of the diverse catfish family is distinguished by a near-total lack of barbels (whisker-like organs near the mouth), the absence of teeth, and colossal size. The largest on record was a female caught in May, 2005, that was 2.7 m (9 feet) long and weighed 293 kg (646 lb).
Like many species in the Mekong, the giant catfish is highly migratory. They’re believed to travel hundreds of miles north from Cambodia’s Tonle Sap Lake to spawning grounds in Thailand, and require specific water conditions in which to spawn, feed, and breed. Overfishing, the damming of Mekong tributaries upstream in China, and habitat destruction have all taken a tremendous toll on the Mekong catfish population. This giant fish is now critically endangered.
", "thumbnail_image":"", "type_attrs":{"_species":"gigas", "_genus":"Pangasianodon", "_family":"Pangasiidae", "_order":"Siluriformes", "_class":"Actinopterygii", "_phylum":"Chordata"}}, "northernleopardfrog":{"print_name":"northern leopard frog", "sort_name":"northern leopard frog", "type":"animal", "definition":"Named for the dark spots on their backs and legs, these are the frogs familiar from biology textbooks and high-school dissection trays. They’re the largest common frog, averaging from 5 to 13 centimeters long (2 to 5 inches) and found in ponds and wetlands across most of northern North America. In the summer they may venture into well-covered grasslands, earning them the name “meadow frog" as well. Adults will eat just about anything they can fit in their mouths (which includes insects, mice, fish, worms, and smaller frogs), and are preyed upon by snakes, raccoons, birds, and humans.
Once North America’s most abundant and widespread frog species, northern leopard frogs rapidly declined in the late 1960s. Large numbers of deformed frogs began turning up in the upper American Midwest in the mid-1990s. Scientists aren’t sure what’s triggering these changes; perhaps parasites, or chemicals in the water that these amphibians inhabit for much of their life cycle. Frogs like these are coming to be seen as “sentinel” species: organisms that react early to environmental pollutants and reflect the health of the entire ecosystem.
", "thumbnail_image":"", "type_attrs":{"_species":"pipiens", "_subgenus":"Lithobates", "_genus":"Rana", "_family":"Ranidae", "_order":"Anura", "_class":"Amphibia", "_phylum":"Chordata"}}, "oceanvents":{"print_name":"hydrothermal vents", "sort_name":"hydrothermal vents", "type":"natural_phenomena", "definition":"When scientists discovered hydrothermal vents more than a mile deep on the ocean floor off the coast of Ecuador in 1977, it was no big surprise. They’d already predicted that hot springs would occur along cracks on the sea floor called mid-ocean ridges, which cover the Earth like seams of a baseball. What was unexpected was the discovery of many kinds of life thriving around the vents—despite the intense cold, crushing pressure, and utter darkness.
Hydrothermal vents form where volcanic activity occurs along these mid-ocean ridges, as molten rock (magma) erupts to form new oceanic crust. Water seeps in below the crust, is heated by the magma, and gushes out of the vent openings at temperatures as high as 400°C (752°F). The scalding water contains dissolved minerals from the volcanic rocks. When it encounters the frigid seawater, a variety of minerals precipitate out as tiny particles. These combine to create shimmering, chimney-like sulfide structures around the vent. Chimneys can be as tall as a 15-story building. These deep-sea vents transfer large amounts of heat and chemical mass from deep within Earth up to its surface.
Deep-sea hydrothermal vents are fascinating from a biological point of view because they support one of the only ecosystems on Earth that doesn’t get its energy directly from the Sun or from photosynthesis. Instead microorganisms use hydrogen sulfide from the vent fluid to produce their own nutrients, a process called chemosynthesis. Biologists think that life on Earth, and even possibly on other planets, may have formed in similar environments.
", "thumbnail_image":"", "type_attrs":{}}, "pompeiiworm":{"print_name":"Pompeii worm", "sort_name":"pompeii worm", "type":"animal", "definition":"Perhaps the most heat-tolerant complex organisms on Earth, Pompeii worms live along ocean floor vents on the Pacific Ocean floor. They tolerate not only total darkness and crushing pressure, but also the toxic mix of chemicals that spews out of the vents at scalding temperatures. Pale gray and about as long as the palm of your hand, the worms live in large colonies enclosed in delicate, paper-thin tubes. They poke their heads out of the tubes to breathe and feed, presumably on vent microbes. Hemoglobin colors the tentacle-like gills on their heads a bright red. At the base of the tubes the water temperature can reach 80°C (176°F), while the worm's head and gills are immersed in water that’s only 22°C (72°F) — quite a difference!
How do Pompeii worms survive? One theory is that the worm dissipates heat through its head, maintaining an internal temperature that does not damage its cells. Other theories involve the worms’ “hairy” backs, which are actually covered with a layer of bacteria that may insulate the worm from blasts of boiling vent water, functioning like a firefighter's heat blanket. The bacteria contain special proteins, enzymes that may protect them — and thus their hosts — from temperature extremes.
", "thumbnail_image":"pompeiiworm.gif", "type_attrs":{"_species":"pompejana", "_genus":"Alvinella", "_family":"Alvinellidae", "_order":"Polychaeta", "_class":"Polychaeta", "_phylum":"Annelida"}}, "tonlesap":{"print_name":"Tonlé Sap, Cambodia", "sort_name":"tonle sap", "type":"place", "definition":"Tonle Sap is the largest freshwater lake in Southeast Asia. For most of the year, the lake covers around 2,700 square km (1680 sq mi) and is around one meter (3 feet) deep. But during the monsoon season, water from the Mekong River reverses direction and pushes water up the Tonle Sap River and into the lake. Nutrients flow upstream and the lake swells to six times its previous size — some 16,000 square km (10,000 sq mi), or nearly one-fifth of the country — with water up to 9 meters (30 feet) deep.
Rather than devastating the region, the floodwaters bring life to the lake. Millions of migratory fishes, from tiny carp to humungous catfish, surge into the lake to breed. These fish are the key to the livelihood of the more than one million people who live around Tonle Sap. Entire villages are built on stilts, or float on pontoons. Birds flock to the floodplain, and rice farms flourish. When the rainy season ends, the flow reverses, carrying the fish down the Mekong River.
Along with 200 species of fish, Tonle Sap is home to 42 species of reptiles, 225 of birds, and 46 of mammals, along with more than 200 plant species. Population growth, dams, and deforestation threaten this productive inland fishery and biodiversity hotspot.
", "thumbnail_image":"", "type_attrs":{"_coordinates":{"longitude":104.066667, "latitude":12.883333}}}, "tufatowers":{"print_name":"tufa towers", "sort_name":"tufa towers", "type":"natural_phenomena", "definition":"These strange-looking spires form when underwater springs rich in calcium flow into lakewater rich in carbonates (found in baking soda). The resulting chemical reaction produces calcium carbonate: common limestone. The presence of other elements such as iron oxide (rust) colors the tufa.
What makes tufa geologically unusual is the way these towers form underwater over freshwater springs, often in a fairly straight line that follows fissures in the lakebed. The spring water is less dense than the lake water, so it rises towards the surface. As it comes into contact with the alkaline lake water, particles of calcium carbonate precipitate (settle out as a solid). Bit by bit, these mineral deposits build a tube or pipe through which the calcium-rich spring water continues to emerge.
Tufa towers grow as high as nine meters (about 30 feet) over the course of several decades. Small currents give them their irregular shape. They form wherever the right chemical environment occurs — even off the coast of Greenland — and become visible as waters recede. Spectacular examples can be found in California’s Mono Lake, where water levels dropped dramatically after the lake was tapped to feed the Los Angeles water supply.
", "thumbnail_image":"", "type_attrs":{}}, "wanderingalbatross":{"print_name":"wandering albatross", "sort_name":"wandering albatross", "type":"animal", "definition":"This seabird has the largest wingspan of any living bird, averaging some 3 meters (10 ft). Aptly named, the Wandering Albatross spends most of its life in flight over the vast oceans of the Southern Hemisphere, landing only to feed or breed. Highly efficient in the air, the birds rarely flap their wings. Instead, a tendon locks the extended wings in place as the birds soar low over the swell, scooping up squid, small fish and floating refuse. Since it may spend several months without touching land, the wandering albatross has evolved to be able to drink salt water. Glands just behind the eye sockets help the bird regulate its balance of water and salts. The glands excrete a highly concentrated salt solution that drains out the bird’s beak, which has a hooked tip and razor-like edges. The albatross also has an acute sense of smell, unusual in a bird, which helps it locate patchily distributed food sources.
Of the world’s 22 species of albatross, 19 are threatened with extinction. The major threat is accidental capture by fishing lines, especially oceanic longlines that target tunas and swordfish.
", "thumbnail_image":"", "type_attrs":{"_species":"exulans", "_genus":"Diomedea", "_family":"Diomedeidae", "_order":"Procellariiformes", "_class":"Aves", "_phylum":"Chordata"}}, "wetlands":{"print_name":"wetlands", "sort_name":"wetlands", "type":"natural_phenomena", "definition":"Swamps, coastal salt marshes, and forest bogs are all wetlands: land where the soil is saturated with moisture. Wetlands are found along coastlines and the edges of streams, rivers, and lakes on every continent except Antarctica. Because they’re so diverse and changeable, wetlands can be hard to recognize. Some are always under water while others are temporary, perhaps changing seasonally from a body of water to a dry field.
Long regarded as wastelands, more than half of America's original wetlands have been destroyed: drained, filled in, or used as dumping grounds. We now understand that they serve many crucial ecological functions. Among the most productive ecosystems in the world, wetlands provide vital habitats for many species of fish, amphibians, reptiles, mammals, and birds, including breeding grounds and shelter for migratory species. Where wetlands are linked to estuaries (where seawater mixes with fresh water), plants and animals must adapt to salty water, fluctuating water levels, and the soil’s low oxygen content.
Wetlands mitigate storm damage by absorbing waves and river currents. By holding surface water much like a sponge and slowly releasing it, swamps and marshes reduce flooding and keep water levels normal. In the process, wetlands filter and purify surface water, absorbing chemicals and excess nutrients before they reach streams or estuaries. Huge numbers of roots holding soil in place and reduce sedimentation, so water leaving a wetland is cleaner than the water coming in. Wetlands are a vital link between water and land.
", "thumbnail_image":"10-wetlands-diorama_med.jpg", "type_attrs":{"ecoregion_type":"freshwater"}}, "frogs":{"print_name":"frogs", "sort_name":"frogs","type":"animal","definition":""}, "glowlighttetra":{"print_name":"glowlight tetra", "sort_name":"glowlight tetra","type":"animal","definition":""}, "chihuahuandesert":{"print_name":"Chihuahuan Desert, North America", "sort_name":"Chihuahuan Desert","type":"place","definition":""}, "texashornedlizard":{"print_name":"Texas horned lizard", "sort_name":"Texas horned lizard","type":"animal","definition":""}, "butterflyorchid": {"print_name":"butterfly orchid", "sort_name":"butterfly orchid","type":"plant","definition":""}, "velamin":{"print_name":"velamin", "sort_name":"velamin","type":"plant","definition":""}, "powderbluesurgeonfish":{"print_name":"powder blue surgeonfish", "sort_name":"powderblue surgeonfish","type":"animal","definition":""}, "shortfinmakoshark":{"print_name":"shortfin mako shark", "sort_name":"shortfin mako shark","type":"animal","definition":""}, "diatom":{"print_name":"diatom", "sort_name":"diatom","type":"animal","definition":""}, "tardigrade":{"print_name":"tardigrade", "sort_name":"tardigrade","type":"animal","type_attrs":{"_species":"testudo","_genus":"Echiniscus"},"definition":"Called "water bears" because of their shape, these microscopic, segmented animals live in water all over the world. Over 900 species have been found everywhere from hot springs and polar ice to Himalayan peaks and the ocean floor. Their ability to tolerate extreme and unpredictable environments makes tardigrades the toughest animals known to science. They've been known to survive oxygen deprivation, freezing and thawing, years without water, and hundreds of times more radiation than any other creature.
Between 0.01 and 1.5 mm long, tardigrades are probably related to arthropods. Most live in fresh water, typically in small droplets of water bound by mosses or lichens on which they feed. Other species, particularly marine species in the deep sea, are carnivorous. Many of their habitats alternate between dry and wet periods; tardigrades wait out droughts by shutting down their metabolism and shriveling up in a ball called a tun.
"}, "dromedarycamel":{"print_name":"dromedary camel", "sort_name":"dromedary camel","type":"animal","definition":""}, "desertcandleeuphorbia":{"print_name":"desert candle euphorbia", "sort_name":"desert candle euphorbia","type":"plant","definition":""}, "mudskipper":{"print_name":"mudskipper", "sort_name":"mudskipper","type":"animal","definition":"Mudskippers are fishes common in intertidal zones throughout tropical and subtropical Africa, Asia, and Australasia. They have special adaptations for life on tidal mudflats and mangrove forests, where they spend most of their time out of water feeding on small animals and algae. These amphibious fishes have two ways of breathing on land. They can absorb oxygen directly through membranes in the back of the mouth or through their skin. They also carry water in enlarged gill chambers, like a scuba diver's tanks. Mudskippers have to replenish this water regularly and keep their skin moist, so they're found near the sea or rolling in puddles. They dig burrows in the mud, where they lay their eggs and can remain completely submerged for up to two hours.
Mudskippers' blunt heads are topped by enormous googly eyes that sit on stalks and can move independently. The eyes periscope above the water when the fish swims, and keep moist on land by retracting into water within the eye sockets (blinking). Mudskippers actually move faster on land than they do in water, "skipping" forward on strong, arm-like pectoral fins. Some species have specially adapted pelvic fins that act like suckers, enabling the fish to move vertically up roots or rocks. These fishes are excellent examples of how vertebrates moved from water to life on land, traversing a formidable ecological barrier.
"}, "northernsnakehead":{"print_name":"northern snakehead", "sort_name":"northern snakehead","type":"animal","type_attrs":{"_species":"argus","_genus":"Channa"},"definition":"The northern snakehead belongs to a family of freshwater fishes native to Africa and Asia, where it's a valuable food source. Believed to have been intentionally released into U.S. waters, snakeheads have become established and are considered a serious threat to native North American fishes. These voracious predators typically grow up to 60-100 cm (2 to 3 ft) and are distinguished by a long dorsal fin, a small head, and long, toothed mouths. Snakeheads devour other fish, along with the occasional small reptile, bird, or mammal. Able to breathe air, they can wriggle across wet ground to new ponds or streams. They can also tolerate a wide range of temperatures and survive for up to four days out of water and longer when burrowed in mud—handy adaptations to wet and dry seasons in their native habitat, and to exploiting new ones. These top-level predators have no natural enemies in North Americas.
"}, "woodfrog":{"print_name":"wood frog", "sort_name":"wood frog","type":"animal","type_attrs":{"_species":"sylvatica","_genus":"Rana"},"definition":"The most widely distributed North American amphibian, wood frogs are found from northern Georgia to north of the Arctic Circle. Since they’re cold-blooded, how do they survive when the mercury dips? In winter, wood frogs make lots of the sugar glucose, which they pump to all parts of their bodies. When the water between the cells freezes, the glucose acts like antifreeze, preventing ice crystals from piercing the frog’s cells. The freezing arrests the frog’s breathing and blood flow, turning the animal’s entire body solid (think frogsicle). When the weather warms, the frog thaws out and hops away.
Lots of insects and plants can tolerate freezing, but only a few vertebrates can pull this off. It enables wood frogs to live in northern environments and to spend the winter on dry land, so they’re not dependent on permanent bodies of water. Though fairly common, in some areas wood frogs are threatened by the loss of wetland to road-building and development.
"}, "emperorpenguin":{"print_name":"emperor penguin", "sort_name":"emperor penguin","type":"animal","type_attrs":{"_species":"forsteri","_genus":"Aptenodytes"},"definition":"The tallest and heaviest penguin species, the emperor penguin stands up to 120 cm (4 feet) tall and can weigh anywhere from 22 to 37 kg (50 to 80 lbs). The bird's weight depends on where it is in its reproductive cycle: both parents lose substantial body mass while breeding during Antarctica's long and brutal winter. Fortunately, blubber, down, and a thick coat of greasy, overlapping feathers protect the birds against winds that blow up to 200 kilometers (124 miles) an hour and water as cold as 2° C (28° F), making the emperor penguin a superb example of adaptation to a harsh environment.
The emperor penguin lives almost exclusively in the Antarctic, almost always breeding on stable pack ice in April or May — wintertime in the Southern Hemisphere. After laying a single egg, the females return to the open ocean to feed, a journey of up to 90 km (56 mi). The males stay put, balancing the eggs on their feet to keep them off the ice and sheltering them in an abdominal pouch. Standing in the pitch-dark cold for up to two months, the expectant fathers huddle together for warmth in groups of up to 6,000 birds. When the females return, recognizing their families through distinct vocalizations, the males leave to take their turn at sea. As the pack ice begins to break up, both chick and parents return to the sea to spend the rest of the summer feeding. Mature adults travel throughout most of the year between the nesting area and the ocean, where they forage in groups for krill, squid, and fish. Black backs and white bellies camouflage them from orcas and seals looking down at the dark water or against the light surface of the water.
"}, "waterphysicalproperties":{"print_name":"water, physical properties", "sort_name":"water, physical properties","type":"natural_phenomena","definition":""}, "ice":{"print_name":"ice", "sort_name":"ice","type":"natural_phenomena","definition":"Ice is the solid state of water. (The other states are liquid water and water vapor, which is a gas.) Ice is abundant on the surface of the Earth, in the Solar System — it's the major component of many moons and comets — and in interstellar space. Ice assumes many forms, including snow, hail, frost, icicles, icebergs, and glaciers.
As water freezes, its molecules become bonded in hexagonal crystals to form the mineral ice. Unlike most substances, water is less dense in its solid state. Its hydrogen bonds become more rigid, causing the molecule to expand, take up more space, and become less dense. That's why ice forms at the top of bodies of water, and why it floats.
The ice stored in Arctic and Antarctic ice sheets and glaciers is a key player in Earth's climate system and the water cycle. Glaciers and ice caps contain 70 percent of the planet's fresh water. Sea ice has a buffering effect on the global climate by melting in the day (absorbing heat from the environment) and refreezing at night (releasing heat), while the temperature changes very little. It also affects global climate by melting during the polar summer and freezing during the polar winter. Because it reflects 90% of the Sun's rays, ice plays an important part in Earth's heat budget (or albedo). Less ice means the Earth absorbs more solar energy, contributing to global warming.
"}, "watervapor":{"print_name":"water vapor", "sort_name":"water vapor","type":"natural_phenomena","definition":"When water molecules escape from the surface of liquid water (evaporation) or ice (sublimation) and float individually into the air, they've turned into a gas called water vapor. You can't see it — mist and clouds are made of tiny droplets of liquid water, not vapor. But the air you breathe is full of it; even air in the middle of the Sahara Desert contains water vapor. Relative humidity is a measure of the amount of water vapor that air at a specific temperature can contain, on a scale of 1 to 100%. Arid deserts have low humidity (less than 10%), while tropical rainforests have very high humidity (more than 75%).
Only a tiny percentage of Earth's water is in the form of vapor, but it plays an essential role in Earth's weather and climate. Without it there would be no clouds, rain or snow, which form when water evaporates from lakes, rivers, and oceans and moves into the atmosphere. Sooner or later, as part of the endless water cycle, all that vapor condenses into water droplets and returns to Earth as rain or snow (precipitation). This process absorbs and releases a significant amount of energy. When liquid water evaporates to form water vapor, heat energy is absorbed, helping to cool the surface of the planet. This energy is released when water vapor condenses to form clouds, fueling thunderstorms, winds, and even hurricanes. Water vapor also accounts for some 95% of Earth's natural greenhouse effect, trapping some of the Sun's heat in the atmosphere and warming the planet.
"}, "waterstrider":{"print_name":"water strider", "sort_name":"water strider","type":"animal","definition":""}, "gulfstream":{"print_name":"Gulf Stream", "sort_name":"Gulf Stream","type":"natural_phenomena","definition":""}, "watercycle":{"print_name":"water cycle", "sort_name":"water cycle","type":"natural_phenomena","definition":"Earth's water moves endlessly between the oceans, the atmosphere, and the land. Powered by energy from the sun, this gigantic system is known as the water cycle. Water changes state (between liquid, vapor, and ice) at various places in the cycle, with some changes happening in a split second and others occurring over millions of years.
Water enters the atmosphere largely through evaporation from lakes, rivers, and oceans. This is responsible for 80% of the water in the atmosphere. Another 10% is produced by plants, which draw water from the soil and return it to the air in a process called transpiration. Sublimation (the process through which water changes from a solid — ice or snow — to a gas) accounts for a tiny bit more, as do volcanic emissions.
After the water enters the lower atmosphere, rising air currents carry it upward. When the water vapor cools below its dew point, it condenses (changes from a gas to a liquid) to form clouds. Within clouds, where water droplets are able to combine and grow in size, precipitation may occur: rain, sleet, hail or snow — depending on conditions in the atmosphere. Precipitation is the main process that transports water from the atmosphere back to the Earth's surface. Some evaporates, returning to the atmosphere. Some soaks into the land, turning into soil moisture or groundwater (water trapped between layers of rock or clay). Most water is groundwater.
Whether underground or on the surface, most of the water flows as runoff into rivers and streams and on into the oceans. There the cycle begins again — or, more accurately, continues. Living things intercept water at every point, and water molecules take infinite paths through the cycle. A water molecule spends about ten days in the air; water in living things can be years to hundreds of years old; parts of the Antarctic ice sheet date back 650 million years; and steam coming out of volcanoes may have been trapped underground for billions of years. The water cycle is the way the Earth uses and recycles water.
"}, "waterorigins":{"print_name":"origins of water", "sort_name":"origins of water","type":"natural_phenomena","definition":""}, "basalticlava":{"print_name":"basaltic lava", "sort_name":"basaltic lava","type":"natural_phenomena","definition":""}, "isuaschist":{"print_name":"Isua schist", "sort_name":"Isua schist","type":"natural_phenomena","definition":""}, "murchisonmeteorite":{"print_name":"Murchison meteorite", "sort_name":"Murchison meteorite","type":"natural_phenomena","definition":"A meteorite is a rock from space that has fallen to Earth. The vast majority are pieces of asteroids, small rocky bodies in orbit between Mars and Jupiter. Such fragments may orbit the Sun for millions of years before colliding with Earth. Since most meteorites are far older than Earth rocks, they are some of the only samples we possess of other worlds. They contain clues to conditions in the early Solar System, how it evolved into the Sun and planets, and the effects — both past and future — of large meteorite impacts. Rare meteorites contain tiny particles that formed around other stars that existed before our Sun. Others are pieces of rock from the surfaces of other planetary bodies such as Mars and the Moon. These fragments were likely blasted planets when the planets were hit by a large asteroid or comet.
When a rock from space hits Earth's atmosphere it turns into a fiery meteor, or "shooting star." Most disintegrate, but an estimated 500 or so reach Earth every year. A tiny percentage (especially those that land on large expanses of ice or sand, where they're easier to spot) are found and made known to scientists. Meteorites are divided into three groups: stony, stony iron (a mix of metal and rock), and iron (almost 98% metal). Stones, which are easily mistaken for ordinary rocks, are the most common. The biggest meteorite ever found weighs around 60 tons, while others are as small as pebbles — or even grains of sand.
"}, "haleboppcomet":{"print_name":"Hale-Bopp Comet", "sort_name":"Hale-Bopp Comet","type":"natural_phenomena","definition":""}, "manhattanschist":{"print_name":"Manhattan schist", "sort_name":"Manhattan schist","type":"natural_phenomena","definition":""}, "gangesriver":{"print_name":"Ganges River, India", "sort_name":"Ganges River","type":"place","definition":""}, "twelveapostlesseastacks":{"print_name":"Twelve Apostles sea stacks, Australia", "sort_name":"Twelve Apostles sea stacks","type":"place","definition":""}, "horseshoefalls":{"print_name":"Horseshoe Falls, Canada", "sort_name":"Horseshoe Falls","type":"place","definition":""}, "rockcycle":{"print_name":"rock cycle", "sort_name":"rock cycle","type":"natural_phenomena","definition":""}, "grandcanyon":{"print_name":"Grand Canyon, Arizona", "sort_name":"Grand Canyon","type":"place","definition":""}, "freshwater":{"print_name":"fresh water", "sort_name":"fresh water","type":"natural_phenomena","definition":""}, "dujiangyanirrigationsystem":{"print_name":"Dujiangyan Irrigation System", "sort_name":"Dujiangyan Irrigation System","type":"artifact","definition":""}, "qindynasty":{"print_name":"Qin Dynasty, China", "sort_name":"Qin Dynasty, China","type":"people","definition":""}, "libing":{"print_name":"Li Bing", "sort_name":"Li Bing","type":"people","definition":""}, "chengduplain":{"print_name":"Chengdu Plain, China", "sort_name":"Chengdu Plain, China","type":"place","definition":""}, "minriver":{"print_name":"Min River, China", "sort_name":"Min River, China","type":"place","definition":""}, "rocksausages":{"print_name":"rock sausages", "sort_name":"rock sausages","type":"artifact","definition":""}, "yuzui":{"print_name":"yuzui (fish snout)", "sort_name":"yuzui (fish snout)","type":"artifact","definition":""}, "dams":{"print_name":"dams", "sort_name":"dams","type":"artifact","definition":""}, "dallesdam":{"print_name":"Dalles Dam", "sort_name":"Dalles Dam","type":"artifact","definition":""}, "nurekdam":{"print_name":"Nurek Dam, Tajikistan", "sort_name":"Nurek Dam, Tajikistan","type":"artifact","definition":""}, "laplatariver":{"print_name":"La Plata River, South America", "sort_name":"La Plata River","type":"place","definition":""}, "danuberiver":{"print_name":"Danube River, Europe", "sort_name":"Danube River","type":"place","definition":""}, "nileriver":{"print_name":"Nile River, Africa", "sort_name":"Nile River","type":"place","definition":""}, "threegorgesdam":{"print_name":"Three Gorges Dam, China", "sort_name":"three gorges dam, China","type":"artifact","definition":""}, "yangtzeriver":{"print_name":"Yangtze River, China", "sort_name":"yangtze river china","type":"place","definition":""}, "chinesesturgeon":{"print_name":"Chinese sturgeon", "sort_name":"Chinese sturgeon","type":"animal","type_attrs":{"_species":"sinensis","_genus":"Acipenser"},"definition":"This ancient fish dates back to the Mesozoic Era, and kept company with dinosaurs and the first mammals on Earth. An adult Chinese sturgeon can be 5 meters (16 feet) long and weigh more than 500 kilograms (over half a ton). After reaching sexual maturity, which can take more than ten years, these giant fish move from seawater to fresh water to spawn. They migrate from the East China Sea up into the Yangtze River, once a journey of some 3,500 kilometers (2,000 miles) — the longest migration of any sturgeon in the world. That was until the Ghezouba Dam was built in the early 1980s, cutting off the sturgeon's migratory path. Spawning grounds have been further reduced by commercial development and massive hydrological projects like the Three Gorges Dam. Although the sturgeon has been protected from commercial fishing since 1983, noise, nets and ship propellers continue to take their toll.
The fish is revered in China, where a captive-breeding center releases hundreds of young sturgeons into the Yangtze every year, but almost all disappear. Today less than 500 adults are believed to survive in the wild. Having existed on Earth for nearly 140 million years, the endangered Chinese sturgeon now faces extinction.
"}, "siberiancranes":{"print_name":"Siberian cranes", "sort_name":"Siberian cranes","type":"animal","definition":""}, "ziguichina":{"print_name":"Zigui, China", "sort_name":"Zigui, China","type":"place","definition":""}, "baculture":{"print_name":"Ba culture", "sort_name":"Ba culture","type":"people","definition":""}, "loireriver":{"print_name":"Loire River, France", "sort_name":"Loire River, France","type":"place","definition":""}, "saintetienneduvigandam":{"print_name":"Saint Etienne du Vigan Dam, France", "sort_name":"Saint Etienne du Vigan Dam, France","type":"artifact","definition":""}, "rooseveltislandtidalenergyproject":{"print_name":"Roosevelt Island Tidal Energy Project", "sort_name":"Roosevelt Island Tidal Energy Project","type":"artifact","definition":""}, "eastrivernewyork":{"print_name":"East River, New York", "sort_name":"East River, New York","type":"place","definition":""}, "wavefarm":{"print_name":"wave farm", "sort_name":"wave farm","type":"artifact","definition":""}, "zapotecculture":{"print_name":"Zapotec culture", "sort_name":"zapotec culture","type":"people","definition":""}, "oaxacavalley":{"print_name":"Oaxaca Valley, Mexico", "sort_name":"Oaxaca Valley","type":"place","definition":""}, "xoxocotlanoaxacamexico":{"print_name":"Xoxocotlan, Oaxaca, Mexico", "sort_name":"Xoxocotlan, Oaxaca, Mexico","type":"place","definition":""}, "corn":{"print_name":"corn", "sort_name":"corn","type":"plant","definition":""}, "teosinte":{"print_name":"teosinte", "sort_name":"teosinte","type":"plant","definition":""}, "irrigation":{"print_name":"irrigation", "sort_name":"irrigation","type":"artifact","definition":""}, "cotton":{"print_name":"cotton", "sort_name":"cotton","type":"plant","definition":""}, "aralsea":{"print_name":"Aral Sea, Asia", "sort_name":"Aral Sea","type":"place","definition":""}, "kazakhstan":{"print_name":"Kazakhstan", "sort_name":"Kazakhstan","type":"place","definition":""}, "uzbekistan":{"print_name":"Uzbekistan", "sort_name":"Uzbekistan","type":"place","definition":""}, "beef":{"print_name":"beef", "sort_name":"beef","type":"artifact","definition":""}, "ogallalaaquifer":{"print_name":"Ogallala Aquifer, U.S.", "sort_name":"Ogallala Aquifer, U.S.","type":"place","definition":""}, "rice":{"print_name":"rice", "sort_name":"rice","type":"plant","definition":""}, "centralvalleycalifornia":{"print_name":"Central Valley, California, US", "sort_name":"Central Valley, California, US","type":"place","definition":""}, "dripirrigation":{"print_name":"drip irrigation", "sort_name":"drip irrigation","type":"artifact","definition":""}, "laserleveling":{"print_name":"laser leveling", "sort_name":"laser leveling","type":"artifact","definition":""}, "lepairrigation":{"print_name":"LEPA (Low-Energy Precision Application) irrigation", "sort_name":"LEPA (Low-Energy Precision Application) irrigation","type":"artifact","definition":""}, "furrowirrigation":{"print_name":"furro irrigation", "sort_name":"furro irrigation","type":"artifact","definition":""}, "khmerempire":{"print_name":"Khmer Empire", "sort_name":"Khmer Empire","type":"people","definition":""}, "angkorwat":{"print_name":"Angkor Wat", "sort_name":"Angkor Wat","type":"artifact","definition":""}, "kingjayavarmanvii":{"print_name":"King Jayavarman VII", "sort_name":"King Jayavarman VII","type":"people","definition":""}, "mekongriver":{"print_name":"Mekong River, Southeast Asia", "sort_name":"Mekong River, Southeast Asia","type":"place","definition":""}, "bonomtouk":{"print_name":"Bon Om Touk", "sort_name":"Bon Om Touk","type":"event","definition":""}, "dai":{"print_name":"dai (Cambodian fishing rig)", "sort_name":"dai","type":"artifact","definition":""}, "treyriel":{"print_name":"trey riel", "sort_name":"trey riel","type":"animal","definition":""}, "prahoc":{"print_name":"prahoc", "sort_name":"prahoc","type":"artifact","definition":""}, "lesseradjutantstork":{"print_name":"lesser adjutant stork", "sort_name":"lesser adjutant stork","type":"animal","definition":""}, "bengalflorican":{"print_name":"Bengal florican", "sort_name":"Bengal florican","type":"animal","definition":""}, "bottomtrawling":{"print_name":"bottom trawling", "sort_name":"bottom trawling","type":"artifact","definition":""}, "martinwillison":{"print_name":"Dr. Martin Willison", "sort_name":"willison martin ","type":"people","definition":""}, "coralreef":{"print_name":"coral reef", "sort_name":"coral reef","type":"animal","definition":""}, "northwestshelfaustralia":{"print_name":"Northwest Shelf, Australia", "sort_name":"Northwest Shelf, Australia","type":"place","definition":""}, "arctic":{"print_name":"Arctic", "sort_name":"Arctic","type":"place","definition":"The Arctic is a vast, ice-covered ocean surrounded by treeless, frozen islands and continental land masses. The boundary is generally considered to be the Arctic Circle (66° 32'N), an imaginary line around the North Pole. North of this line, 24-hour sunlit days and 24-hour sunless nights occur at least once a year, and periods of almost continuous daylight or night last up to six months. Midwinter temperatures can average -40°C (-40°F), and much of the Arctic Ocean is permanently covered with a 3-meter (10-feet) thick layer of drifting pack ice that sunlight seldom penetrates. During the winter, this Arctic ice pack grows to the size of the United States; in the summer, half disappears. Despite these harsh conditions, this ecosystem teems with life, from polar bears and ice-dwelling bacteria to musk ox roaming the tundra and millions of migrating seabirds. Unlike Antarctica, the Arctic is inhabited by humans — Inuits and other indigenous people.
One of the world's last and largest wildernesses, the Arctic environment has been changing fast over the last two decades. The air is warmer, permafrost is decreasing, and the extent of sea ice is shrinking steadily. These changes may be related to global warming caused by industrialized nations releasing of greenhouse gases into the atmosphere. Models predict that the summer ice cover will completely disappear by the 2080s, with serious ecological consequences.
"}, "polarbear":{"print_name":"polar bear", "sort_name":"polar bear","type":"animal","type_attrs":{"_species":"maritimus","_genus":"Ursus"},"definition":"Polar bears are the top predators of the Arctic ice. They migrate hundreds of kilometers to stay on pack ice, which extends south in the winter and retreats north as it melts in summer. These massive marine mammals — males weigh up to 770 kg (1700 lbs) — can swim up to 100 kilometers (60 miles) between ice floes, and dive underwater to ambush prey from below. Broad feet act like paddles to propel them through water and distribute their weight on the sea ice. Because of climate change, the Arctic ice cap is shrinking fast. Without ice the bears have no way to stalk and capture seals, their staple food. Although they have evolved to live off of their fat reserves when food is scarce, this shorter seal-hunting season threatens their survival in regions such as Hudson Bay. As a result, polar bears are listed as globally Vulnerable by the World Conservation Union.
Adaptations enable polar bears to survive conditions too harsh for other bears. Their coats have water-repelling guard hairs and dense underfur to ward off the frigid Arctic water. Females, who hibernate only when pregnant, produce milk with a high fat content that helps the cubs survive temperatures as low as -45° Celsius (-50° Fahrenheit). Recent evidence suggests that females are producing fewer and smaller cubs because of reduced food supplies.
"}, "iditarodrace":{"print_name":"Iditarod race", "sort_name":"Iditarod race","type":"event","definition":""}, "inuitanimalcarvings":{"print_name":"Inuit animal carvings", "sort_name":"Inuit animal carvings","type":"artifact","definition":""}, "polarbearcarving":{"print_name":"polar bear carving", "sort_name":"polar bear carving","type":"artifact","definition":""}, "whalecarving":{"print_name":"whale carving", "sort_name":"whale carving","type":"artifact","definition":""}, "waterfowlcarving":{"print_name":"waterfowl carving", "sort_name":"waterfowl carving","type":"artifact","definition":""}, "sealheadbutton":{"print_name":"seal head button", "sort_name":"seal head button","type":"artifact","definition":""}, "egyptianvase":{"print_name":"Egyptian vase", "sort_name":"Egyptian vase","type":"artifact","definition":""}, "watercarriers":{"print_name":"water carriers", "sort_name":"water carriers","type":"artifact","definition":""}, "mangbetuwatervessel":{"print_name":"Mangbetu water vessel", "sort_name":"Mangbetu water vessel","type":"artifact","definition":"A people of the Democratic Republic of the Congo, the Mangbetu are known for their art and music. They subsist by farming small plots and raising cattle, along with some fishing, hunting, and gathering. The Mangbetu are believed to have migrated from the northeast (present-day Sudan), intermarrying with and subsuming many of the Bantu and pygmy populations they encountered. Around 1800 a number of small chiefdoms were consolidated into the first Mangbetu kingdom, whose tradition of courtly prestige and cultural exchange encouraged the arts. European explorers were impressed by the kingdom's political institutions and by its architecture, pottery, and sculpture. The Mangbetu were also set apart by their elongated heads, created by tightly wrapping the heads of their babies in cloth.
The Mangbetu kingdom was fragmented when Islamic slavers entered the region in 1880; the slavers were in turn expelled by Belgian colonists. Western photographers and film-makers were drawn to their distinctive culture during the first half of the 20th century, and contemporary Mangbetu art is widely collected.
Today in the Congo, only 45% of people have access to safe drinking water and in some rural areas, this is as low as 3%.
"}, "afghanwatervessel":{"print_name":"Afghan water vessel", "sort_name":"Afghan water vessel","type":"artifact","definition":""}, "jerrycan":{"print_name":"Jerry can", "sort_name":"Jerry can","type":"artifact","definition":""}, "arapeshwatercarrier":{"print_name":"Arapesh water carrier", "sort_name":"Arapesh water carrier","type":"artifact","definition":""}, "capotitlanwaterjar":{"print_name":"Capotitlan water jar", "sort_name":"Capotitlan water jar","type":"artifact","definition":""}, "netsilikwatercarrier":{"print_name":"Netsilik water carrier", "sort_name":"Netsilik water carrier","type":"artifact","definition":""}, "bedouinwaterpail":{"print_name":"Bedouin water pail", "sort_name":"Bedouin water pail","type":"artifact","definition":""}, "indianwatercarrier":{"print_name":"Indian water carrier", "sort_name":"Indian water carrier","type":"artifact","definition":""}, "watersupply":{"print_name":"water supply", "sort_name":"water supply","type":"artifact","definition":""}, "watergatherers":{"print_name":"water gathering", "sort_name":"water gatherers","type":"artifact","definition":""}, "villagepump":{"print_name":"village pump", "sort_name":"village pump","type":"artifact","definition":""}, "varanasiindia":{"print_name":"Varanasi, India", "sort_name":"Varanasi, India","type":"place","definition":""}, "puja":{"print_name":"puja", "sort_name":"puja","type":"event","definition":""}, "ritualvessel":{"print_name":"Indian ritual vessel", "sort_name":"Indian ritual vessel","type":"artifact","definition":""}, "indianritualspoon":{"print_name":"figure with uddharane", "sort_name":"figure with uddharane","type":"artifact","definition":""}, "veerbhadramisra":{"print_name":"Veer Bhadra Misra", "sort_name":"Veer Bhadra Misra","type":"people","definition":""}, "qdrum":{"print_name":"Q-drum", "sort_name":"Q-drum","type":"artifact","definition":""}, "rainwaterharvestingjar":{"print_name":"rainwater harvesting jar", "sort_name":"rainwater harvesting jar","type":"artifact","definition":""}, "melbourneaustralia":{"print_name":"Melbourne, Australia", "sort_name":"Melbourne, Australia","type":"place","definition":""}, "yemenistepwell":{"print_name":"Yemeni step well", "sort_name":"Yemeni step well","type":"artifact","definition":""}, "petrajordan":{"print_name":"Petra, Jordan", "sort_name":"Petra, Jordan","type":"place","definition":""}, "saltwater":{"print_name":"saltwater", "sort_name":"saltwater","type":"natural_phenomena","definition":""}, "galapagosmarineiguana":{"print_name":"Galapagos marine iguana", "sort_name":"Galapagos marine iguana","type":"animal","definition":"Most iguanas can swim, but the Galapagos marine iguana is the only sea-going lizard in the world. It's an excellent example of adaptation to its habitat: the Galapagos Islands off the Pacific coast of Ecuador. These large lizards — the larger and more brightly colored males grow up to 1.2 meters (4 feet) or more, almost half being tail — live on land. Herbivores, they graze on algae on rocks in the intertidal zone or on submerged pastures. The largest iguanas swim past the breakers and dive as deep as 15 meters (50 feet) to forage. Long, sharp claws help them hold fast to rocks battered by waves, and blunt snouts enable them to scrape off the algae. Salt swallowed while feeding is concentrated in a gland that drains into the animal's nasal passages and is ejected in occasional "sneezes." Some of the spray, which is much saltier than seawater, often lands on the iguana's head, coating it white.
When they emerge from the cold Galapagos waters, marine iguanas warm themselves by sunbathing on black rocks near the shore. At night they often huddle together to conserve heat.
The marine iguana has few natural predators, but is threatened by rats, cats, and dogs that have been introduced to the islands.
"}, "reverseosmosisfiltermembrane":{"print_name":"reverse osmosis filter membrane", "sort_name":"reverse osmosis filter membrane","type":"artifact","definition":""}, "perthaustralia":{"print_name":"Perth, Australia", "sort_name":"Perth, Australia","type":"place","definition":""}, "deserts":{"print_name":"deserts", "sort_name":"deserts","type":"natural_phenomena","definition":""}, "unitedarabemirates":{"print_name":"United Arab Emirates", "sort_name":"United Arab Emirates","type":"place","definition":""}, "scottsdalearizona":{"print_name":"Scottsdale, Arizona", "sort_name":"Scottsdale, Arizona","type":"place","definition":""}, "lasvegasnevada":{"print_name":"Las Vegas, Nevada", "sort_name":"Las Vegas, Nevada","type":"place","definition":""}, "mesacountycolorado":{"print_name":"Mesa County, Colorado", "sort_name":"Mesa County, Colorado","type":"place","definition":""}, "saudiarabia":{"print_name":"Saudi Arabia", "sort_name":"Saudi Arabia","type":"place","definition":""}, "dubai":{"print_name":"Dubai", "sort_name":"Dubai","type":"place","definition":""}, "tucsonarizona":{"print_name":"Tucson, Arizona", "sort_name":"Tucson, Arizona","type":"place","definition":""}, "alainoasisabudhabi":{"print_name":"Al Ain oasis, Abu Dhabi", "sort_name":"Al Ain oasis, Abu Dhabi","type":"place","definition":""}, "palmspringscalifornia":{"print_name":"Palm Springs, California", "sort_name":"Palm Springs, California","type":"place","definition":""}, "fogcatching":{"print_name":"fog catching", "sort_name":"fog catching","type":"artifact","definition":""}, "namibdesertbeetle":{"print_name":"Namib Desert beetle", "sort_name":"Namib Desert beetle","type":"animal","type_attrs":{"_species":"gracilipes","_genus":"Stenocara"},"definition":"These large, long-legged beetles live in southwestern Africa's Namib Desert, where annual rainfall averages less than 40 mm (1 1/2 inches). The most reliable source of moisture is the damp, early-morning breeze that sweeps in from the chilly Atlantic Ocean. Fog condenses when this breeze mixes with the hot, dry desert air, and the Namib beetle survives by collecting it. The insect faces into the damp wind. Minute water droplets condense around bumps on the beetle's back, combine, and grow — until they're heavy enough to pull away and roll down into the beetle's mouth. Scientists are hoping to recreate this technique in large-scale efforts to harvest water from fog. The Namib desert beetle's other adaptations to its harsh environment include a thick shell that provides insulation and reduces moisture loss through evaporation. Long legs lift and move the insect rapidly over the scorching sand in search of the windblown vegetation and animal matter on which it feeds.
"}, "invasiveplants":{"print_name":"invasive plants", "sort_name":"invasive plants","type":"plant","definition":""}, "workingforwatersouthafrica":{"print_name":"Working for Water, South Africa", "sort_name":"Working for Water, South Africa","type":"people","definition":""}, "southafrica":{"print_name":"South Africa", "sort_name":"South Africa","type":"place","definition":""}, "fynbos":{"print_name":"fynbos", "sort_name":"fynbos","type":"plant","definition":""}, "playpump":{"print_name":"Play Pump", "sort_name":"Play Pump","type":"artifact","definition":""}, "bottledwater":{"print_name":"bottled water", "sort_name":"bottled water","type":"artifact","definition":""}, "cholerabacteria":{"print_name":"cholera", "sort_name":"cholera","type":"animal","definition":""}, "johnsnow":{"print_name":"John Snow", "sort_name":"John Snow","type":"people","definition":""}, "copepods":{"print_name":"copepods", "sort_name":"copepods","type":"animal","definition":""}, "indiansari":{"print_name":"Indian sari", "sort_name":"Indian sari","type":"artifact","definition":""}, "lifestrawfilter":{"print_name":"Lifestraw filter", "sort_name":"Lifestraw filter","type":"artifact","definition":""}, "waterpollution":{"print_name":"water pollution", "sort_name":"water pollution","type":"artifact","definition":""}, "xenopuslaevis":{"print_name":"African clawed frog", "sort_name":"african clawed frog","type":"animal","definition":"","type_attrs":{"_species":"laevis","_genus":"Xenopus"}}, "antibacterialsoap":{"print_name":"antibacterial soap", "sort_name":"antibacterial soap","type":"artifact","definition":""}, "rotifers":{"print_name":"rotifers", "sort_name":"rotifers","type":"animal","definition":""}, "oscillatoria":{"print_name":"oscillatoria", "sort_name":"oscillatoria","type":"animal","definition":""}, "giardia":{"print_name":"giardia", "sort_name":"giardia","type":"animal","definition":""}, "cryptosporidium":{"print_name":"cryptosporidium", "sort_name":"cryptosporidium","type":"animal","definition":""}, "euglena":{"print_name":"euglena", "sort_name":"euglena","type":"animal","definition":""}, "didinium":{"print_name":"didinium", "sort_name":"didinium","type":"animal","definition":""}, "nakivuboswamp":{"print_name":"Nakivubo Swamp, Uganda", "sort_name":"Nakivubo Swamp","type":"place","definition":""}, "lakevictoriauganda":{"print_name":"Lake Victoria, Uganda", "sort_name":"Lake Victoria, Uganda","type":"place","definition":""}, "kampalauganda":{"print_name":"Kampala, Uganda", "sort_name":"Kampala, Uganda","type":"place","definition":""}, "greatlakes":{"print_name":"Great Lakes, US", "sort_name":"Great Lakes, US","type":"place","definition":""}, "bullfrog":{"print_name":"bullfrog", "sort_name":"bullfrog","type":"animal","definition":""}, "brownbullhead":{"print_name":"brown bullhead", "sort_name":"brown bullhead","type":"animal","definition":"","type_attrs":{"_species":"nebulosus","_genus":"Ameiurus"}}, "northernpike":{"print_name":"northern pike", "sort_name":"northern pike","type":"animal","definition":"","type_attrs":{"_species":"lucius","_genus":"Esox"}}, "pickerelweed":{"print_name":"pickerel weed", "sort_name":"pickerel weed","type":"plant","definition":"","type_attrs":{"_species":"cordata","_genus":"Pontederia"}}, "waterlily":{"print_name":"water lily", "sort_name":"water lily","type":"plant","definition":"","type_attrs":{"_species":"odorata","_genus":"Nymphaea"}}, "northernwatersnake":{"print_name":"northern water snake", "sort_name":"northern water snake","type":"animal","definition":"","type_attrs":{"_species":"sipedon","_genus":"Nerodia"}}, "commonsnappingturtle":{"print_name":"common snapping turtle", "sort_name":"common snapping turtle","type":"animal","definition":"","type_attrs":{"_species":"serpentina","_genus":"Chelydra"}}, "muskrat":{"print_name":"muskrat", "sort_name":"muskrat","type":"animal","definition":"","type_attrs":{"_species":"zibethicus","_genus":"Ondatra"}}, "pumpkinseedsunfish":{"print_name":"pumpkinseed sunfish", "sort_name":"pumpkinseed sunfish","type":"animal","definition":"","type_attrs":{"_species":"gibbosus","_genus":"Lepomus"}}, "yellowperch":{"print_name":"yellow perch", "sort_name":"yellow perch","type":"animal","definition":"","type_attrs":{"_species":"flavescens","_genus":"Perca"}}, "arrowhead":{"print_name":"arrowhead plant","sort_name":"arrowhead plant","type":"plant","definition":"","type_attrs":{"_species":"latifolia","_genus":"Sagittaria"}}, "broadleafedcattail":{"print_name":"broad-leafed cattail", "sort_name":"broad-leafed cattail","type":"plant","definition":"","type_attrs":{"_species":"latifolia","_genus":"Typha"}}, "duckweed":{"print_name":"duckweed", "sort_name":"duckweed","type":"plant","definition":"","type_attrs":{"_genus":"Lemna"}}, "softstembulrush":{"print_name":"softstem bulrush", "sort_name":"softstem bulrush ","type":"plant","definition":"","type_attrs":{"_species":"tabernaemontani","_genus":"Schoenoplectus"}}, "twelvespottedskimmer":{"print_name":"twelve-spotted skimmer", "sort_name":"twelve-spotted skimmer","type":"animal","definition":"","type_attrs":{"_species":"pulchella","_genus":"Libellula"}}, "greenfrog":{"print_name":"green frog", "sort_name":"green frog","type":"animal","definition":""}, "easternpaintedturtle":{"print_name":"eastern painted turtle", "sort_name":"Eastern painted turtle","type":"animal","definition":"","type_attrs":{"_species":"picta","_genus":"Chrysemys"}}, "redwingedblackbird":{"print_name":"red-winged blackbird", "sort_name":"red-winged blackbird","type":"animal","definition":"","type_attrs":{"_species":"phoeniceus","_genus":"Agelaius"}}, "groundwater":{"print_name":"groundwater", "sort_name":"groundwater","type":"natural_phenomena","definition":"Did you know that there's far more water — 30 to 100 times as much! — under the surface of the Earth as in all its rivers and lakes? That's groundwater: rain and snow that seeps down between particles of soil and into the cracks and pore spaces in solid rock. These spaces can fill with water like a sponge, creating aquifers below the water table. Aquifers can occur close to the surface or hundreds of feet deep. Depending on the nature of the surrounding rock, water can take days or millions of years to move through aquifers.
Groundwater makes up 30% of Earth's fresh water resources. It's an important component of the water cycle, forming springs, oases and wetlands. Like river water, groundwater is susceptible to pollution and overuse. Billions of people rely on groundwater for drinking, farming, and industry. It picks up substances in the surrounding rock, and when those substances are harmful, so is the water. When we pump it out faster than it can accumulate, the level (or water table) drops below the reach of ever-deeper wells — sometimes hundreds of feet. The ground may sink, saltwater may seep in, and that water is no longer available to replenish local springs and streams.
"}, "subsidence":{"print_name":"subsidence", "sort_name":"subsidence","type":"natural_phenomena","definition":""}, "sanjoaquinvalleycalifornia":{"print_name":"San Joaquin Valley, California", "sort_name":"San Joaquin Valley, California","type":"place","definition":""}, "bangladesh":{"print_name":"Bangladesh", "sort_name":"Bangladesh","type":"place","definition":""}, "aquifer":{"print_name":"aquifer", "sort_name":"aquifer","type":"natural_phenomena","definition":""}, "sandstone":{"print_name":"sandstone", "sort_name":"sandstone","type":"natural_phenomena","definition":""}, "dolomite":{"print_name":"dolomite", "sort_name":"dolomite","type":"natural_phenomena","definition":""}, "granite":{"print_name":"granite", "sort_name":"granite","type":"natural_phenomena","definition":""}, "reclaimedwater":{"print_name":"reclaimed water", "sort_name":"reclaimed water","type":"artifact","definition":""}, "ultravioletlight":{"print_name":"ultraviolet light", "sort_name":"ultraviolet light","type":"natural_phenomena","definition":""}, "windhoeknamibiaafrica":{"print_name":"Windhoek, Namibia, Africa", "sort_name":"Windhoek, Namibia, Africa","type":"place","definition":""}, "aquaticecosystems":{"print_name":"aquatic ecosystems", "sort_name":"aquatic ecosystems","type":"natural_phenomena","definition":""}, "mesopotamia":{"print_name":"Mesopotamia", "sort_name":"Mesopotamia","type":"place","definition":""}, "tigris":{"print_name":"Tigris River, Asia", "sort_name":"Tigris","type":"place","definition":""}, "euphrates":{"print_name":"Euphrates River, Asia", "sort_name":"Euphrates","type":"place","definition":""}, "madan":{"print_name":"Ma'dan", "sort_name":"Ma'dan","type":"people","definition":""}, "syria":{"print_name":"Syria", "sort_name":"Syria","type":"place","definition":""}, "turkey":{"print_name":"Turkey", "sort_name":"Turkey","type":"place","definition":""}, "iran":{"print_name":"Iran", "sort_name":"Iran","type":"place","definition":""}, "iraq":{"print_name":"Iraq", "sort_name":"Iraq","type":"place","definition":""}, "gardenofeden":{"print_name":"Garden of Eden", "sort_name":"Garden of Eden","type":"place","definition":""}, "sumer":{"print_name":"Sumer", "sort_name":"Sumer","type":"people","definition":""}, "cuneiformtablet":{"print_name":"cuneiform tablet", "sort_name":"Cuneiform tablet","type":"artifact","definition":""}, "rivers": {"print_name":"rivers", "sort_name":"rivers","type":"natural_phenomena","definition":""}, "fish": {"print_name": "fish", "sort_name":"fish", "type":"animal","definition":""}, "birds": {"print_name": "birds", "sort_name": "birds", "type":"animal", "definition":""}, "mississippiriverdelta": {"print_name": "Mississippi River Delta", "sort_name": "mississippi river delta", "type":"place", "definition":""}, "monolake": {"print_name": "Mono Lake, California", "sort_name": "mono lake", "type":"place", "definition":""}, "paiutepeople": {"print_name": "Paiute Native Americans", "sort_name": "paiute native americans", "type":"people", "definition":""}, "californiagull":{"print_name":"California gull", "sort_name":"california gull","type":"animal","definition":"","type_attrs":{"_species":"californicus","_genus":"Larus"}}, "painting":{"print_name":"paintings", "sort_name":"painting","type":"artifact","definition":""}, "quotation":{"print_name":"quotations", "sort_name":"quotation","type":"artifact","definition":""}, "geology":{"print_name":"geology", "sort_name":"geology","type":"natural_phenomena","definition":""}, "agriculture":{"print_name":"agriculture", "sort_name":"agriculture","type":"artifact","definition":""}, "seaice":{"print_name":"sea ice", "sort_name":"sea ice","type":"natural_phenomena","definition":"Sea ice is a solid, layer of frozen seawater that blankets millions of square kilometers of the Polar Oceans and about 7 percent of the world's oceans. It plays a crucial role in global climate by reflecting solar radiation and by insulating relatively warm water from the cooler atmosphere. In the Antarctic almost all sea ice melts away each summer, while in the Arctic some persists year after year. In recent years the extent of summer ice cover over the Arctic Ocean has shrunk drastically; large portions that were permanently covered are now open water. Computer models predict that the summer Arctic ice cover will completely disappear by the 2080s. This has serious implications for sea levels, global ocean circulation, and the survival of species like polar bears and ringed seals that hunt, feed, and breed on the ice.
Because seawater is salty, the top layer starts to freeze at about -1.8 °C (28.8 °F). The salt molecules are rejected as the water freezes; sea ice is no saltier than the ice in your cooler. Depending on temperature, waves, and wind, sea ice comes in many shapes and sizes. For example, it can be attached to the coast (fast ice) or float freely (drift ice) or be compacted into large masses (pack ice). Ice floes and ice fields are floating chunks of sea ice, while icebergs — because they're made of compacted snow from glaciers — are not. Sea ice is part of the Earth's biosphere and is home to many organisms.
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