An Enormous Arctic Spiral

Looking south across the southern tip of Greenland, this satellite image shows an enormous cloud vortex spiraling over the northern Atlantic ocean on January 26, 2013. An example of the powerful convection currents in the upper latitudes, these polar low cyclones are created when the motion of cold air is energized by the warmer ocean water beneath.

Sometimes referred to as Arctic cyclones, these spiraling storms can bring gale-force winds and heavy snowfall over a wide area of ocean during their 12- to 36-hour lifespans. Hurricane-type storms don’t only form in the tropics!

This image was captured by the MODIS instrument on NASA’s Aqua satellite from its polar orbit 705 km (438 miles) above the Earth. The view has been rotated so south is up; the southernmost tip of Greenland can be seen at lower right. Click for an impressive high-resolution view.

Image via EOSNAP/Chelys

NASA Satellite Sees Ghostly Remains of Vanishing Arctic Sea Ice

Sea ice swirls in ocean currents off the coast of Greenland (NASA/GSFC)

Spooky spectral swirls of last season’s sea ice drift in currents off the coast of eastern Greenland in this image from NASA’s Aqua satellite, acquired on October 17. Although sea ice in the Arctic will start forming again after September’s record low measurements, these ghostly wisps are likely made up of already-existing ice that has migrated south.

As global temperatures rise — both over land and in the ocean — thinner sea ice builds up during the Arctic winter and thus more of it melts during the summer, a pattern that will eventually lead to an ice-free Arctic if trends continue. The past several years saw sea ice in the Arctic below the 1979-2000 average, with this past September displaying the lowest volumes yet recorded.

The graph below, made from data modeled by the Polar Science Center at the University of Washington, show the chilling — or, perhaps, not-so-chilling — results of this century’s recent observations.

Along Greenland’s east coast, the Fram Strait serves as an expressway for sea ice moving out of the Arctic Ocean. The movement of ice through the strait used to be offset by the growth of ice in the Beaufort Gyre.

Until the late 1990s, ice would persist in the gyre for years, growing thicker and more resistant to melt. Since the start of the twenty-first century, however, ice has been less likely to survive its trip through the southern part of the Beaufort Gyre. As a result, less Arctic sea ice has been able to pile up and form multi-year ice.

Thin, free-drifting ice — as seen above — moves very easily with winds and currents.

Aqua is a NASA Earth Science satellite mission named for the large amount of information that the mission is collecting about the Earth’s water cycle, including evaporation from the oceans, water vapor in the atmosphere, clouds, precipitation, soil moisture, sea ice, land ice, and snow cover on the land and ice. Aqua was launched on May 4, 2002, and carries six Earth-observing instruments in a near-polar low-Earth orbit. MODIS, which acquired the image above, is a 36-band spectroradiometer that measures physical properties of the atmosphere, oceans and land.

Source: NASA Earth Observatory

NASA image courtesy Jeff Schmaltz, LANCE MODIS Rapid Response Team at NASA GSFC. Graph by Jesse Allen based on modeled ice volume data from the Polar Science Center, University of Washington. Caption portions by Michon Scott with information from Ted Scambos, National Snow and Ice Data Center.

Pacific Glory

An optical phenomenon known as a “glory” is seen over a cloud-covered Pacific Ocean in this image from NASA’s Aqua satellite, acquired on June 20, 2012. Although the colors may make it look like a rainbow, the process behind its formation is somewhat different.

As vortices spiral off the leeward side of Guadalupe Island, off the western coast of Baja California, a shimmering spectrum of colors highlights a glory just west of the island. Glories are created when light from the Sun reflects back toward an observer off water droplets within clouds or fog. They are often seen from airplanes as a bright ring of light encircling a silhouetted shadow of the aircraft below, but are also visible from the ground and, sometimes, even from space.

From the NASA Earth Observatory website:

Although glories may look similar to rainbows, the way light is scattered to produce them is different. Rainbows are formed by refraction and reflection; glories are formed by backward diffraction. The most vivid glories form when an observer looks down on thin clouds with droplets that are between 10 and 30 microns in diameter. The brightest and most colorful glories also form when droplets are roughly the same size.

From the ground or an airplane, glories appear as circular rings of color. The space shuttle Columbia observed a circular glory from space in 2003. In the image above, however, the glory does not appear circular. That’s because MODIS scans the Earth’s surface in swaths perpendicular to the path followed by the satellite. And since the swaths show horizontal cross sections through the rings of the glory, the glory here appears as two elongated bands of color that run parallel to the path of the satellite, rather than a full circle.

Glories always appear around the spot directly opposite the Sun, from the perspective of the viewer. This spot is called the anti-solar point. To visualize this, imagine a line connecting the Sun, a viewer, and the spot where the glory appears. In this case, the anti-solar point falls about halfway between the two colored lines of the glory.

Click here to download the full-size image.

NASA image courtesy Jeff Schmaltz, LANCE MODIS Rapid Response. Read more here.

Tropical Storm Debby Douses the Gulf

The eastern Gulf of Mexico is getting lashed by tropical storm Debby, which whipped up tornado-spawning winds and dumped inches of rain across much of Florida, Mississippi, Alabama and southern Georgia over the weekend. NASA’s Aqua satellite acquired this image on June 23, just after the depression strengthened to full tropical storm status.

Born over the warm, moist air of the Gulf off the coast of Mississippi on Saturday afternoon, Debby quickly strengthened to storm status with sustained winds currently reported at over 60 mph. Slow-moving at a 6 mph crawl to the northeast, Debby continues to drench the Gulf state coasts with inches of rain — up to 10 to 20 inches projected for some areas. Major flooding has already become a problem and reports of tornadoes have been coming in since Sunday afternoon.

Debby will likely become a hurricane at some point, although her future path is still not entirely known.

Launched on May 4, 2002, NASA’s Aqua satellite specializes in keeping track of the movement of water around the planet in all its various forms. Find out more about the Aqua mission here.

Image: NASA/GSFC/Jeff Schmaltz/MODIS Land Rapid Response Team

Huge Wildfires Burn on Opposite Sides of the Planet

The latest views of Earth from NASA’s Aqua and Terra satellites are looking a bit hazy from wildfires burning in wilderness areas of the United States and Siberia.

The above image acquired July 18 from the Moderate Resolution Imaging Spectroradiometer, or MODIS, aboard the Terra satellite, shows a whopping 198 wildfires burning across Siberia. You can view more of this huge fire at NASA’s Earth Observatory website. The fires have charred an area of more than 83 square kilometers. Some of the fires were started by people who lost control of agricultural fires but some fires were started by lightning.

High Park Fire from NASA's Aqua MODIS
Another NASA earth-observing satellite, Aqua, has taken dramatic images of the High Park Fire just west of Fort Collins, Colorado and the Whitewater-Baldy Complex Fire in southwestern New Mexico. The High Park Fire has grown to more than 235 square kilometers, burning 180 structures and leading to the death of one person. It has become one of the most destructive and largest fires in Colorado history. Thankfully, the

Besides measuring the smoke plume and fire extent, much can be learned using satellite images of wildfires. Types of vegetation can affect the type and color of smoke emitted by the wildfire. Grassland fires tend to burn quickly and give off carbon-rich black smoke. Forest fires where moisture is higher give off thicker smoke; a combination of organic rich ash and water vapor, that ranges in color from brown to bright white.

Pyrocumulus cloud from High Park Fire, ColoradoOn the plus side for weather buffs, each of the fires have produced rare pyrocumulus, or fire clouds. Wildfires and volcanos can produce these dramatic clouds as intense heating causes the air to rise. As the rising air cools, water vapor in the ash cloud condenses just like a normal cloud. The ash particles provide nuclei for water to condense. Sometimes this moisture will fall back on the fire as rain. Dave Lipson, a meteorologist with the National Oceanic and Atmospheric Administration told the Denver Post that calm and clear weather along Colorado’s Front Range made the towering pyrocumulus cloud look especially menacing Tuesday. Tuesday afternoon, the lone fire cloud could be seen from 40 miles away from Denver.

Lead image caption: NASA image courtesy Jeff Schmaltz, LANCE MODIS Rapid Response. Instrument: Terra – MODIS

Second image caption: High Park Fire, Colorado from NASA’s Aqua MODIS

Third image caption: Looking north near Boulder, Colorado at the pyrocumulus cloud produced from the High Park Fire. Photo: John Williams

There’s a Hole in the Sky!

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Well, not the sky exactly, but definitely in the clouds!

This image, acquired by NASA’s Aqua satellite on June 5, shows an enormous oval hole in the clouds above the southern Pacific Ocean, approximately 500 miles (800 km) off the southwestern coast of Tasmania. The hole itself is several hundred miles across, and is the result of high pressure air in the upper atmosphere.

According to Rob Gutro of NASA’s Goddard Space Flight Center, “This is a good visible example of how upper-level atmospheric features affect the lower atmosphere, because the cloud hole is right under the center of a strong area of high pressure. High pressure forces air down to the surface blocking cloud formation. In addition, the altocumulus clouds are rotating counter-clockwise around the hole, which in the southern hemisphere indicates high pressure.”

The northwestern tip of Tasmania and King Island can be seen in the upper right of the image.

The Aqua mission is a part of the NASA-centered international Earth Observing System (EOS). Launched on May 4, 2002, Aqua has six Earth-observing instruments on board, collecting a variety of global data sets about the Earth’s water cycle. Read more about Aqua here.