Why Might One Find Tundra, Glacier, And Polar Conditions At Low Latitudes?

Sea Level Pressure in the Arctic

The map of sea level pressure level for October 1 to 30, 2010, shows a high-pressure arrangement cenetered over the Beaufort and Chukchi bounding main and Greenland, and low pressure over the Kara and Barents seas. This design tends to bring warm air from lower latitudes into the Arctic. —Credit: National Snow and Ice Data Center courtesy NOAA/ESRL PSD

The unique geography of the Arctic leads to unique weather patterns that reappear in the region year after year. Some weather patterns, such every bit cyclones or anticyclones, are mutual exterior the Arctic. The Arctic Oscillation is an atmospheric circulation pattern that occurs over the mid-to-loftier latitudes of the Northern Hemisphere, including the Arctic.

Weather condition patterns that recur or persist over multiple seasons are called semipermanent highs and lows, considering these patterns show upward in long-term averages of the regional weather.

Cyclones and Anticyclones

Cyclones, or low-pressure systems, are circular weather patterns that rotate in a counter clockwise management. In a cyclone, air moves upward in the middle of the pattern, bringing stormy wet weather. In the Arctic, cyclones occur twelvemonth circular, only they tend to happen more in certain places depending on the time of twelvemonth. Semipermanent lows in the Chill include the Aleutian Low, a low-pressure center that experiences many cyclones and storms in the winter, and the Icelandic Low, a low-pressure center located about Republic of iceland.

Diagram of a cyclone and an anticyclone

Left: Whirlwind, Right: Anticyclone
—Credit: K. Ritter/University of Wisconsin Stevens Signal

Anticyclones are the opposite of cyclones, high-pressure systems that rotate in a clockwise direction. An anticyclone known as the Beaufort High recurs yr after twelvemonth, sitting over the Beaufort Sea and Canadian Archipelago in winter and spring. An anticyclone too frequently appears over Siberia, known as the Siberian High.

Polar Lows

Arctic Cyclone

Whirlwind over the Chill Ocean.
—Credit: NASA/MODIS

Polar lows are pocket-size, intense cyclones that course over open up bounding main during the cold season. From satellite imagery, polar lows can wait much similar a hurricane, with a large spiral of clouds centered effectually an centre—for this reason they are sometimes called Arctic hurricanes. Polar lows range in size from around 100 to 500 kilometers (62 to 310 miles) in diameter. Wind speeds average effectually 50 miles per hour, although they can occasionally reach hurricane strength (64 miles per hr).

Polar lows tend to form when cold Chill air flows over relatively warm open water. The storms can develop rapidly, reaching their maximum strength within 12 to 24 hours of formation, just they dissipate just as quickly, lasting on average only one or two days.

Semipermanent Highs and Lows

Weather maps bear witness the circulation and pressure level patterns over i or several days. But maps of sea level pressure tin also be averaged over several months or years, to show the average circulation patterns in the atmosphere. These averaged maps remove some of the variability caused by day-to-day weather condition changes, instead showing longer-term patterns that can touch weather and climate both within and outside of the Arctic.

Researchers compare the relative strengths of semipermanent highs and lows, and report these comparisons in indices such as the N Atlantic oscillation and the Chill oscillation. These indices take been linked to variability in temperatures and to sea water ice conditions in the Arctic.

Explore Farther: Semipermanent Patterns lists some important semipernament patterns.

Chill Oscillation

The Arctic Oscillation refers to an opposing pattern of pressure between the Chill and the northern middle latitudes. Overall, if the atmospheric pressure level is loftier in the Arctic, information technology tends to be low in the northern middle latitudes, such as northern Europe and N America. If atmospheric pressure is depression in the eye latitudes it is oftentimes high in the Arctic. When pressure is loftier in the Chill and low in mid-latitudes, the Arctic Oscillation is in its negative phase. In the positive phase, the pattern is reversed.

Meteorologists and climatologists who study the Arctic pay attention to the Arctic Oscillation, considering its stage has an important effect on weather condition in northern locations. The positive phase of the Arctic Oscillation brings ocean storms further north, making the conditions wetter in Alaska, Scotland, and Scandinavia and drier in the western United states and the Mediterranean. The positive phase also keeps weather warmer than normal in the eastern Usa, only makes Greenland colder than normal.

In the negative phase of the Arctic Oscillation the patterns are reversed. A strongly negative stage of the Arctic Oscillation brings warm weather to high latitudes, and cold, stormy weather to the more than temperate regions where people alive. Over near of the past century, the Arctic Oscillation alternated between its positive and negative phase. For a catamenia during the 1970s to mid-1990s, the Chill Oscillation tended to stay in its positive stage. However, since and then it has again alternated betwixt positive and negative, with a record negative stage in the winter of 2009-2010.

Arctic Oscillation Diagram

Left: Effects of the Positive Stage of the Arctic Oscillation. Right:Furnishings of the Negative Phase of the Arctic Oscillation. —Credit: J. Wallace, University of Washington.

Explore Farther: Semipermanent Patterns

The semipermanent patterns listed below are centers of action in the Arctic atmosphere, influencing weather patterns in the Arctic and around the world.

Aleutian Low: This semipermanent low-pressure center is located well-nigh the Aleutian Islands. Well-nigh intense in winter, the Aleutian Depression is characterized by many strong cyclones. Traveling cyclones formed in subpolar latitudes in the North Pacific usually slow down and reach maximum intensity in the area of the Aleutian Low.
Icelandic Low: This depression-pressure center is located near Iceland, ordinarily betwixt Iceland and southern Greenland. Most intense during winter, it weakens and splits into two centers in summer, one near Davis Strait and the other west of Iceland.
Azores Loftier: The Azores Loftier is a high-pressure pattern that forms in the subtropical Atlantic Ocean. Although it occurs outside the Arctic Ocean, information technology is linked to the Icelandic Depression through the North Atlantic oscillation.
Siberian High: The Siberian High is an intense, common cold anticyclone that forms over eastern Siberia in winter, associated with frequent cold air outbreaks over eastern asia.
Beaufort Loftier: The Beaufort High is a loftier-pressure center over the Beaufort Sea present mainly in winter.
North American Loftier: The North American High is a relatively weak expanse of loftier pressure that covers about of North America during wintertime. This pressure organization tends to exist centered over the Yukon, simply is not also-defined as its continental counterpart, the Siberian High.