The Russian Heat Wave: Why is it So Hot?

August 3, 2010; 1:27 PM ET
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The Russian heartland has reeled this summer under deadly severe heat that has only been made worse by debilitating drought and wildfires.

Moscow has its hottest month in 130 years of records, including its highest temperature ever recorded.

Average temperatures for the month of July were fully 15 F above normal, and since the start of summer, average temperatures have been a staggering 13.8 F above normal.

Fires are blazing where normally the land is lush and well-watered with green woods and crops.

The Associated Press reports that tens of thousands of firefighters and volunteers were battling wildfires that have killed at least 40 people and destroyed several thousand homes so far. Smoke from these fires has enveloped Moscow with smog.

Hundreds more have drowned in swimming mishaps while trying to cool off from the relentless heat.

So what exactly is the cause of this unusual, severe heat in an area usually accustomed to moderate, moist summers?

"Clues can be found in the upper atmosphere of the middle latitudes, where the ever-present winds of the jet stream hold sway," said AccuWeather.com Senior Meteorologist Jim Andrews.

According to Andrews, a strong upper-atmospheric high, or ridge, built over European Russia toward the beginning of summer. In doing so, it diverted the jet stream and its rain-giving train of summer storms farther north than usual, giving much of the area drought conditions this summer.

In addition, southern desert heat from central Asia, the Arabian Peninsula and North Africa began to flow northward, which strengthened this ridge and tightened its hold over the region.

Land parched by drought normally tends to heat more than well-watered land, as evaporation works as a cooling agent, Andrews said.

"The land and the atmosphere above it answer by becoming hotter," he said. "This, in turn, strengthens the upper ridge and its ability to shunt away cooling, rain-bearing storms riding the steering winds of the jet stream."

The increase in temperature, the increase in evaporation and the drying of the ground create a "vicious cycle" in that each condition continues to intensify, and it is unclear which condition came first, which Andrews refers to as a "chicken or the egg" conundrum.

Whatever the case, the cycle seems to have kicked in with profound effect for millions in the Russian heartland.

So, what will it take to break the iron-clad upper ridge and the heat and drought it has created?

According to Andrews, this pattern will run its course eventually, as strong sunshine of long Russian summer days will inevitably give way as the seasons progress.

"Rain-giving storms will break down the ridge followed by the cold and snow of the long Russian winter," he said.

In the meantime, heat and drought will grip greater Moscow through at least Sunday with abnormal heat for at least another week in southern Russia.

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