Russian Drought / Pakistan Floods / Atlantic Hurricanes

As the old song goes, the foot-bone is connected to the ankle-bone, the ankle-bone is connected to the shin-bone, the shin-bone is connected to the knee-bone…. This is true of just about everything in life. I’ve used it for computer trouble shooting for 30 some years. Parents use it in child rearing — How did that happen? [“It just did,” is seldom the right answer.] It’s a basic truism of human knowledge that there are no causeless events. Science is essentially a centuries long discovery of causes and effects, many of which we do not know, some of which we may never know. Religion, since the time of the neanderthal has a filler called God for any uncaused event.

Connection and cause are also true of weather systems. Problem is, our knowledge of the parts and connections is just about where knowledge of the human body was back when Leonardo smuggled corpses into his studio to study their composition. We don’t have near enough data, or interpretive schema to understand the weather-body as we now do the human one but it’s interesting when some large areas begin to be visible. For example:

Jeff Masters: In summer 2010, Pakistan got Russia’s rain

[The weather we experience is stirred in ways we don’t understand very well by the high-altitude jet streams that circle from west to east, in an undulating (snake like) pattern around the globe. The loops affect high and low pressure zones which in turn affect dryness and moisture in the air, within those zones. wbk]

Jeff Masters: The drought in Russia was caused by a jet stream pattern that took the jet stream far to the north of Russia, and kept low pressure systems that usually go over the country from dropping their rain.

At the same time, part of the jet stream veered south, he said.

The jet stream looped over Pakistan as the yearly monsoon rains were occurring. The monsoon consists of air currents rising over heated land, which lets moisture-laden air flow in from the oceans. Masters said it was hot in Pakistan this summer also. So the monsoon was unusually heavy.

Jeff Masters: When you have hot air like that, it tends to have more water vapor. So now we had an exceptionally strong flow of moist air off the oceans that had a much higher water content than usual. And that’s a recipe for heavy rainfall and heavy flooding.

Channel 4 news in England tells a similar story, though instead of a simple high and low loop as Masters describes, Tom Clark shows a bifurcating jet stream, sending the southern arm down over Pakistan and doing as Masters has it.

The stream has split in two. One arm has gone north, another south. The patch in the middle is Russia’s drought. A circulating pattern of air has been sitting over Russia for far longer than normal, causing the extreme temperatures and wildfires they’ve had there.

But what’s happening over Pakistan is even stranger. The southern arm of the Jet stream has looped down so far it has crossed over the Himalayas into north western Pakistan. Experts at the Met Office tell me this is very unusual.

And the result is that the fast moving jets stream winds high up has helped suck the warm, wet, monsoon air even faster and higher into the atmosphere – and that has caused rains like no-one can remember. It has turbo charged the monsoon if you like. They’re not sure that’s ever happened before.

And if those linkages aren’t interesting enough, how about this one? The same pattern looks like it delayed the on-set of the Atlantic hurricane season and explains why the expected high number of storms did not materialize in August.

Forecasters had predicted that warm sea-surface temperatures and the onset of the weather pattern known as La Niña would make a busy Atlantic hurricane season this year. In June, Phil Klotzbach and William Gray of Colorado State University predicted 18 tropical storms, with 10 reaching hurricane force and five becoming deadly major hurricanes. The US National Oceanic and Atmospheric Administration forecast similar numbers.

La Niña arrived on schedule this year, and sea-surface temperatures were at record highs in July and August in the main area where Atlantic storms develop, says Klotzbach. Yet little happened there, and the Pacific was eerily quiet, with no July cyclones in its eastern half for the first time since 1966. Klotzbach attributes the calm conditions to dry air subsiding over the oceans, denying tropical storms the moisture that powers their growth.

Stalled wind

The dry air came from the blocking pattern that stalled the jet stream over Russia and Pakistan, says Judith Curry of the Georgia Institute of Technology in Atlanta. Air rose over Europe and Asia, then descended over the oceans depleted of the atmospheric moisture that fuels hurricanes.

“When the heatwave broke in Russia, that’s when hurricanes started forming,” says James Done of the National Center for Atmospheric Research in Boulder, Colorado. Four tropical storms formed in the tropical mid-Atlantic from 21 August to 1 September. The first two, Danielle and Earl, both became powerful major hurricanes, with Earl now affecting the US east coast.

New Scientist

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