Image of the Day Archive
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Above: Warning: Bison in rear view mirror may be closer than they appear.
The driver of the car in the above undated photo found this out first-hand when the car was caught in a bison "traffic jam" in Yellowstone National Park.
The bison is the largest land mammal in North America. They can weigh more than half a ton. Despite their size, bison can run up to 30 mph (50 km/h). That's more than fast enough to keep up with traffic on wintery roads in Yellowstone.
This herd was large enough to intimidate, but it's a mere fraction of the Yellowstone bison population, which fluctuates between 2,300 and 4,500 animals. There are two subpopulations within Yellowstone bison, the Northern Range and Hayden Valley herds, which are divided based on their gathering for breeding.
Bison were nearly extinct in the 19th century due to hunting, slaughter and bovine diseases from domestic cattle. Today, Yellowstone is the only place in the lower 48 states where a population of wild bison has persisted since prehistoric times.
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Among the Mangroves
A medley of warm colors fills the sky in this stunning photo of the Florida Bay, which separates the main part of the state from the Florida Keys. Researchers at the U.S. Geological Survey captured this scene of the sun setting behind a mangrove island, at the south end of Everglades National Park.
The Everglades are complex system of interdependent ecosystems, including marshes, swamps, mangrove forests and rocklands.
Everglades National Park protects 20 percent of the original Everglades. The national park attracts about a million visitors each year, and is the third-largest national park in the lower 48 states, according to the National Park Service. Everglades National Park, which was established on Dec. 6, 1947, has also been declared an International Biosphere Reserve, a World Heritage Site and a Wetland of International Importance. [Related Photos: Giant Pythons Invade Everglades]
An Astronaut's View
La Malinche mountain, an inactive volcano in Mexico, looms large in this photo taken Oct. 29 by an astronaut aboard the International Space Station. A dusting of snow at the summit, and deep canyons that cut into the flanks of the eroded volcano, can be seen in the eye-catching image.
La Malinche is a so-called stratovolcano, located approximately 19 miles (30 kilometers) northeast of Puebla, Mexico. Stratovolcanoes are steep, conical structures that are composed of layers of ash, lava and rocks that were released from previous explosive eruptions.
An examination of volcanic rocks at La Malinche suggests the structure erupted near the end of the 12th century. Researchers have also found evidence of mudflows that indicate an eruption occurred about 3,100 years ago, which would have affected Pre-Columbian settlements in the nearby Puebla basin, according to NASA. [Related: The 10 Biggest Volcanic Eruptions in History]
Postcard From An Expedition
The midday sun blankets the Antarctic landscape in warm colors in this eye-catching scene. The photo, taken in July, shows scientists from the Alfred Wegener Institute for Polar and Marine Research, headquartered in Germany, preparing for a day of work on the sea ice.
A team of 49 scientists and 44 crewmembers embarked on a three-month expedition to Antarctica in June. The researchers examined properties of Antarctic sea ice and studied changes in the region's ecosystems. [Related: Extreme Living – Scientists at the End of the Earth]
Seal of Approval
Perk up your Friday with this adorable picture of a southern elephant seal. These photogenic creatures are prolific swimmers, able to dive as deep as 5,000 feet (1,500 meters) and remain underwater for 20 to 30 minutes, according to experts at the World Conservation Society (WCS).
The WCS is studying southern elephant seals as part of the organization's Sea and Sky project, which helps protect the Patagonian Sea and its surrounding coastal regions, which make up one of the largest and richest marine ecosystems in the world. [Related Photos: Elephant Seals of the Antarctic]
Sea of Fog Shrouds Grand Canyon
You won't know it by looking at the above picture, but there's a 1-mile-deep (1.6 kilometer) canyon under that fog.
This breathtaking fog filled the Grand Canyon last week, transforming the rocky Arizona landmark into something seemingly coastal. The fog formed during a rare weather event known as a temperature inversion, which happen just a few times each year.
Calm winds, clear skies and long winter nights are ideal conditions for temperature inversions. When these conditions mingle, a layer of cool air at the canyon floor can become trapped underneath warmer air. This is opposite of the usual weather pattern, since temperature generally decreases with altitude. When moisture is trapped in this cool layer of air, fog can form.
Last week, a text-book temperature inversion in the Grand Canyon created a sea of fog across the 18-mile-wide (28.9 kilometers) gap, which was carved by Colorado River and stretches 277 miles (446 km). [Related: 7 Amazing Grand Canyon Facts]
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Eyes Over Antarctica
In late November, NASA scientists conducted a short ice-surveying mission to Antarctica. The researchers spent a week snapping aerial photographs of the icy continent and collecting scientific data on the thickness of ice over Antarctica's subglacial lakes, mountains and frozen seas.
In five science flights, totaling 43 hours, the researchers collected data over more than 12,000 miles (20,000 kilometers). This photo, taken on Nov. 24, shows a so-called lenticular cloud hovering near Mount Discovery, a volcano located about 44 miles (70 km) southwest of McMurdo Station on Antarctica's Ross Island.
Lenticular clouds form when a layer of air near the surface encounters a topographic barrier, gets forced upward, and flows over it as a series of atmospheric gravity waves. The clouds form at the crest of the waves, where the air is coolest and water vapor can condense into cloud droplets.
The Antarctic flights were part of NASA's Operation IceBridge, a multi-year mission to monitor ice conditions in Antarctica and the Arctic. [Related: Stunning Photos of Antarctic Ice]
The sun sets over the east side of Montana's Glacier National Park in this breathtaking photo. The region, located along the border between Canada and the United States, is bathed in color as the sun descends in the evening sky.
Glacier National Park encompasses a 1,500-square-mile (4,000 square kilometers) area, which includes forests, lakes, mountains and alpine meadows. In this photo, Mount Cleveland, the highest mountain in Glacier National Park, can be seen on the left. [Related: All Yours: 10 Least Visited National Parks]
Rock-A-Bye Baby Sloth
A female two-toed sloth was born recently at the Rosamond Gifford Zoo in Syracuse, N.Y. The baby sloth, named Araña, was born on Aug. 1, and has been hand-reared by zoo staff since she was four days old, according to officials at the Rosamond Gifford Zoo.
Sloths are native to Central America and northern South America, including portions of Peru and central Brazil. These nocturnal animals typically sleep for 15 hours or more each day, and are notoriously slow-moving.
Two-toed sloths have long limbs with two curved claws on its front feet and three on its hind. This enables them to hang upside down from tree limbs, and move deftly through tree tops and canopies. [Related: World's Cutest Baby Animals]
It's the Most Wonderful Times of the Year
Are you dreaming of a white Christmas? The National Oceanic and Atmospheric Administration (NOAA) crunched the data and released a fun map that shows which U.S. states have the highest probability of seeing a white Christmas this year, based on the agency's trove of historic weather data. [Related: Images of Stunning Snowy Landscapes]
If you're in Idaho, Minnesota, Maine or upstate New York, you may be in luck this holiday season. Areas around the Rocky Mountains, Sierra Nevada Mountains and the Allegheny Mountains of Pennsylvania and West Virginia may also be in store for a white Christmas.
The map displays the historic probability of there being at least 1-inch (2.5 centimeters) of snow on the ground in the lower 48 states on Dec. 25. The dark gray patches show places where the probability is less than 10 percent, while the swirls of white on the map indicate places where the probability is greater than 90 percent.
NOAA's National Climatic Data Center used weather data from 1981 to 2010 to build the festive map. To keep track of snowfall across the U.S. on a daily basis, the NCDC also maintains a daily snowfall map. [Related: Top 11 Christmas Gifts for Geeks]
Dreaming of a White Christmas in Arches National Park
The soaring red rocks of Arches National Park are coated in snow, just in time for a white Christmas.
The park, in Moab, Utah, is under a winter advisory as many trails are snowy, icy and dangerous, according to the park's website.
Arches National Park is known as a landscape of contrasting colors, and the red rocks and white snow make that even more apparent in winter. In this park, visitors will also find landforms and textures unlike any other in the world.
The most famous feature in Arches National Park is the Delicate Arch, a 65-foot-tall (19.8 meters) freestanding natural arch. Delicate Arch is so famous that it's on Utah's license plates.
The park has over 2,000 natural stone arches, in addition to hundreds of soaring pinnacles, massive fins and giant balanced rocks. This red rock wonderland will amaze hikers with its formations, trails, sunsets ... and snow.