Arctic sea ice is in constant motion. It rides on the ocean, absorbing energy from the circumpolar weather systems.
This movement causes a buildup of stress within the ice. Under enough stress, the ice cracks or buckles in a cataclysmic process that resembles the energy released in earthquakes. These continuous ice quakes result in open leads of water or mountainous ridges of broken, jumbled ice. These deformations, in turn, may have an effect on the thickness and durability of the arctic ice pack in the face of climate change.
University of Alaska Fairbanks researcher Jennifer Hutchings hopes that a better understanding of this complex process will help improve climate models and shed light on how sea ice behaved in the past and how it may change in the future.
Earth Changes
Tornadoes are the most violent storms on Earth. Winds spiraling into them usually exceed 100 mph and can reach speeds of 300 mph. In the USA, an average of 1,000 tornadoes spin up beneath thunderstorms each year, and these typically kill about 60 people.
Tornadoes and the threat of tornadoes are a key part of the USA's spring weather because spring brings favorable tornado conditions. But tornadoes can occur any time of the year, during the day and at night.
Tornadoes and the threat of tornadoes are a key part of the USA's spring weather because spring brings favorable tornado conditions. But tornadoes can occur any time of the year, during the day and at night.
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| ©NOAA Photo Library |
| An F2 tornado roars near Seymour, Texas, in April 1979. F2 and F3 tornadoes are considered strong, packing winds of 113-206 mph that can cause major to severe damage. |
OKLAHOMA CITY - A tornado as wide as two football fields carved a devastating path through an eastern Colorado town as a massive spring storm swept from the Rockies into the Plains, killing at least four people in three states, authorities said Thursday.
Sixty-five tornadoes were reported in Oklahoma, Texas, Kansas, Colorado and Nebraska on Wednesday, the National Weather Service said.
KANSAS CITY, Mo. - Residents of the Plains states huddled for cover early Thursday as a major storm system that has killed at least two people moved through the region, bringing heavy snow and tornadoes to some areas.
Severe weather warnings and watches were in effect from South Dakota to Texas, as authorities warned residents to stay alert for tornado warnings.
Severe weather warnings and watches were in effect from South Dakota to Texas, as authorities warned residents to stay alert for tornado warnings.
Weather is a hot topic here in Interior Alaska and a quick way to get anyone talking. Not a day goes by in winter months without some observations of temperatures, air inversions, or even a mention that the sun budged another degree above the horizon.
When it comes to predicting weather events, however, particularly the extreme events - such as harsh winds, impact from massive wildfires or ash resulting from volcanic eruptions - those who work in the field face many challenges in creating models specific for Alaska's unique environment.
When it comes to predicting weather events, however, particularly the extreme events - such as harsh winds, impact from massive wildfires or ash resulting from volcanic eruptions - those who work in the field face many challenges in creating models specific for Alaska's unique environment.
Although it's been more than a year since Mount Augustine had its memorable eruption, work continues for University of Alaska Fairbanks researchers. The work of Alaska Volcano Observatory employees from UAF's Geophysical Institute will be appearing in the upcoming issue of the journal Science.
The article, which came out on Feb. 23, documents electrical activity that occurred during the January 2006 eruption of Mount Augustine. While it has long been known that volcanic eruptions can produce vigorous lightning, there are few direct observations of the phenomena, states the article. Following the initial eruptions of Jan. 11 and 13, 2006, two of which produced lightning, two electromagnetic lightning detectors were set up in Homer about 60 miles from Augustine. A couple of days later, the volcano erupted again, with the first of four eruptions producing a "spectacular lightning sequence."
The article, which came out on Feb. 23, documents electrical activity that occurred during the January 2006 eruption of Mount Augustine. While it has long been known that volcanic eruptions can produce vigorous lightning, there are few direct observations of the phenomena, states the article. Following the initial eruptions of Jan. 11 and 13, 2006, two of which produced lightning, two electromagnetic lightning detectors were set up in Homer about 60 miles from Augustine. A couple of days later, the volcano erupted again, with the first of four eruptions producing a "spectacular lightning sequence."
Mount Klyuchevskaya has started emitting lava on the Kamchatka Peninsula and another volcano in Russia's Far East, Shiveluch, spewed out gas and ash, a local geophysics service said Thursday.
Klyuchevskaya, one of the world's highest active volcanoes, rising to a height of 4,750 meters (15,584 feet), is emitting lava at an altitude of 4,200-4,300 meters (about 14,000 feet), the service said.
"The authorities should warn people about a possible danger and take proper security measures," said Alexei Ozerov, a senior seismology researcher, adding that the lava flow would grow more powerful.
Streams of lava with a temperature of about 1,100 C( (2,012 F() are encountering ice caps, producing powerful explosions of vapor. Experts are warning of devastating mudflows that can reach 500 meters (1,640 feet) in width and can descend the volcano's eastern slopes.
Klyuchevskaya, one of the world's highest active volcanoes, rising to a height of 4,750 meters (15,584 feet), is emitting lava at an altitude of 4,200-4,300 meters (about 14,000 feet), the service said.
"The authorities should warn people about a possible danger and take proper security measures," said Alexei Ozerov, a senior seismology researcher, adding that the lava flow would grow more powerful.
Streams of lava with a temperature of about 1,100 C( (2,012 F() are encountering ice caps, producing powerful explosions of vapor. Experts are warning of devastating mudflows that can reach 500 meters (1,640 feet) in width and can descend the volcano's eastern slopes.
It was a rare sight over Melbourne, with eye-catching mammatus clouds drifting in from the west.
The clouds were bluish-grey with a distinctive cellular pattern of pouches.
They were hanging under another cloud base -- a sure sign of rain to come.
The clouds were bluish-grey with a distinctive cellular pattern of pouches.
They were hanging under another cloud base -- a sure sign of rain to come.
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| ©Mark Smith |
| Menacing sky: mammatus clouds herald an approaching cold front. |
The Himalaya, the "Roof of the World", source of the seven largest rivers of Asia are, like other mountain chains, suffering the effects of global warming. To assess the extent of melting of its 33 000 km2 of glaciers, scientists have been using a process they have been pioneering for some years. Satellite-imagery derived glacier surface topographies obtained at intervals of a few years were adjusted and compared. Calculations indicated that 915 km2 of Himalayan glaciers of the test region, Spiti/Lahaul (Himachal Pradesh, India) thinned by an annual average of 0.85 m between 1999 and 2004. The technique is still experimental, but it has been validated in the Alps and could prove highly effective for watching over all the Himalayan glacier systems. However, the procedure for achieving a reliable estimate must overcome a number of sources of error and approximation inherent in satellite-based observations.
The researchers started by retrieving satellite data for two periods, 2000 and 2004. A digital field model was extracted for each of them, representing the topography of a ground reference point in digital form and therefore usable in computerized processing. The earliest topography of the area studied was provided by NASA which observed 80% of the Earth's surface during the Shuttle Radar Topographic Mission of February 2000. Then, in November 2004, two 2.5 m resolution images of the same area taken at two different angles were acquired especially by the French satellite Spot5 in the framework of an ISIS (CNES) project.
The researchers started by retrieving satellite data for two periods, 2000 and 2004. A digital field model was extracted for each of them, representing the topography of a ground reference point in digital form and therefore usable in computerized processing. The earliest topography of the area studied was provided by NASA which observed 80% of the Earth's surface during the Shuttle Radar Topographic Mission of February 2000. Then, in November 2004, two 2.5 m resolution images of the same area taken at two different angles were acquired especially by the French satellite Spot5 in the framework of an ISIS (CNES) project.
Tropics and subtropics may develop new climates.
A new climate modeling study forecasts the complete disappearance of several existing climates in tropical highlands and regions near the poles, while large swaths of the tropics and subtropics may develop new climates unlike any seen today.
In general, the models show that existing climate zones will shift toward higher latitudes and higher elevations, squeezing out the climates at the extremes--tropical mountaintops and the poles--and leaving room for unfamiliar climes and new ecological niches around the equator.
The work, by researchers at the University of Wisconsin-Madison and the University of Wyoming, appears online in the journal Proceedings of the National Academy of Sciences (PNAS) during the week of March 26. The National Science Foundation (NSF) funded the research.
The most severely affected parts of the world span both heavily populated regions, including the southeastern United States, southeastern Asia, and parts of Africa, and known hotspots of biodiversity, such as the Amazonian rainforest and African and South American mountain ranges.
A new climate modeling study forecasts the complete disappearance of several existing climates in tropical highlands and regions near the poles, while large swaths of the tropics and subtropics may develop new climates unlike any seen today.
In general, the models show that existing climate zones will shift toward higher latitudes and higher elevations, squeezing out the climates at the extremes--tropical mountaintops and the poles--and leaving room for unfamiliar climes and new ecological niches around the equator.
The work, by researchers at the University of Wisconsin-Madison and the University of Wyoming, appears online in the journal Proceedings of the National Academy of Sciences (PNAS) during the week of March 26. The National Science Foundation (NSF) funded the research.
The most severely affected parts of the world span both heavily populated regions, including the southeastern United States, southeastern Asia, and parts of Africa, and known hotspots of biodiversity, such as the Amazonian rainforest and African and South American mountain ranges.
