If the Himalayas didn't exist?

[cheeky_monkey]

Simple starter for 10..how would the world's weather patterns change if the Himalayas did not exist?

[knocker]

You are a wag cm.

[Lettucing Gutted]

In the short term south asia, especially India and Pakistan and Nepal and Bangladesh will get colder, especially in autumn, winter and spring, as frigid Continental Polar and Arctic air masses would no longer be barred by the Himalayas from surging due south from Siberia.  On the other hand eastern asia including Siberia, Mongolia, Japan, Vietnam, Korea, Malaysia, Thailand and China would get hotter as hot Continental Tropical and Maritime Tropical air masses from India, Pakistan and the North Indian Ocean will no longer be barred by the Himalayas from soaring due northeast and east.  The warming in the far east would also be enhanced by the weakened Northeast Winter Monsoon caused the rapid and strong warming of Siberia. 

However in the long term there would be Global Warming as there would be less chemical weathering to remove CO2 out of the atmosphere.

Edited May 1, 2016 by Lettucing Gutted

[davehsug]

How does this work? If the sub-continent didn't exist the Himalayas wouldn't.

[knocker]

And where would we be without mountain torque? Doesn't bear thinking about.

[BornFromTheVoid]

Central Asia would probably get some impressive summer storms like the US if the Himalayas were removed.

[cheeky_monkey]

On ‎02‎/‎05‎/‎2016 at 3:28 PM, BornFromTheVoid said:

Central Asia would probably get some impressive summer storms like the US if the Himalayas were removed.

And tornadoes in the transition seasons like the US?

[BornFromTheVoid]

12 minutes ago, cheeky_monkey said:

And tornadoes in the transition seasons like the US?

Probably to even more of an extreme.

[mountain shadow]

Monsoon rainfall in Bangladesh and flooding would be much less as no mountains to increase the rainfall.

[iapennell]

On 5/2/2016 at 14:24, knocker said:

And where would we be without mountain torque? Doesn't bear thinking about.

Without the Himalayas intercepting the strong upper westerlies in winter, the need for a sink for accumulated atmospheric westerly momentum (caused by easterlies in both high and low latitudes) would need to be satisfied elsewhere. It means stronger and more persistent Westerlies in mid-latitudes would occur so Britain would become even wetter and stormier than it currently is!! There would be less likelihood of blocking patterns over Scandinavia and even less cold easterly winds in winter than now.

Summers will be cooler and wetter!

For sure, that does not bear thinking about!!

[iapennell]

It is certain that the higher mid-latitudes would become the sink for the AAM currently absorbed by the Himalayas in winter. This undoubtedly means more wet and windy weather in all seasons but particularly in winter. 

It has to be said, however that the upper Westerlies are usually well north of the Himalayas even in winter these days because of the contracted Circumpolar Vortex in response to less Arctic pack-ice and a warmer North Atlantic and North Pacific. The contracted Circumpolar Vortex tends to be associated with high zonal index with a strong subtropical high centred about 35N and deep depressions in the sub-arctic in winter. In such situations the Himalayas is not a sink for much (if any) westerly AAM and the North Atlantic and Pacific and into western Canada and NW Europe take over almost all this role. And if it were possible to remove the Himalayas we would get winters like that of 2013-14 and 2015-16 in Britain all the time. 

The highest latitudes would probably cool in such a situation because a persistently strong Circumpolar Vortex would give little chance for very cold Arctic air to drain away southwards. This would serve to intensify the baroclinic gradient between the Arctic and mid-latitudes which would only serve to intensify the storms affecting Britain. Heavier snow and colder conditions on the Greenland Icecap would lead to the ice thickening and help allay some of the concerns about global warming. 

Without the Himalayas the seasonal heating through a considerable depth of the atmosphere over central southern Asia would not be as great and the monsoons would be weaker. Cool dry air would penetrate across the Indian sub-continent in winter and the net result of all this would be that much of southern Asia would become desert with a belt of savanna further south with consequences for many millions of Indians and Chinese folk that hardly bear thinking about! 

Persistent high zonal index circulation in higher latitudes with strong Westerlies means that high-pressure will dominate the Mediterranean through winter and spring as well as the summer with the consequence being that countries bordering the Mediterranean will become extremely dry with extensive areas turning to desert. Similar latitudes across the US and China\Japan will also become dry.

[iapennell]

On the other hand, plonking another Himalayan sized mountain range in the North Atlantic around 50 to 60N would directly intercept the Circumpolar Vortex and act as a sink for most accumulated westerly AAM winter and summer. This would lead to extremely cold winters and warm dry summers in Britain as the prevailing winds become easterly. 

I discuss the destruction of the Ferrel Westerlies here if folk are interested :

https://www.netweather.tv/forum/topic/86193-the-ferrel-westerlies-would-weakening-them-cool-the-north/

 

[Frost HoIIow]

The main reason India & Pakistan are quite mild in Winter is the Himalayas block cold air from Russia surging south into those two countries. As a poster above says if those mountains weren't there India & Pakistan would be colder in Winter. The Himalayas are so tall & so wide that they have a huge impact on the weather in India, Pakistan & Bangladesh. It's like in Florida look how far south it is and they can get frost and even some snow in the northern part of the state that's because there is no big mountain range to the north of Florida to block cold air moving south from Canada.

Edited September 6, 2016 by Frost HoIIow

[cheese]

4 hours ago, Frost HoIIow said:

The main reason India & Pakistan are quite mild in Winter is the Himalayas block cold air from Russia surging south into those two countries. As a poster above says if those mountains weren't there India & Pakistan would be colder in Winter. The Himalayas are so tall & so wide that they have a huge impact on the weather in India, Pakistan & Bangladesh. It's like in Florida look how far south it is and they can get frost and even some snow in the northern part of the state that's because there is no big mountain range to the north of Florida to block cold air moving south from Canada.

Yeah. Look at Brownsville in Texas - 25 degrees north of the equator yet has a record low of -12C, and in 2011 went an entire day below freezing. It has an average high of 21C and an average low of 11C in January. In December 2004, it had a white Christmas!

The standard deviation in the US in winter is remarkably high, and as you say it's because there's no west-east mountain range to block the Arctic air. It just floods down freely. Even tropical Miami has seen sub-freezing temperatures. Nowhere else in the world has such ridiculous variations on a day to day basis. Heck, certain subtropical climates in the US can't even grown certain palm species that can grow in England because they get too many hard freezes.

Edited September 7, 2016 by cheese

[iapennell]

On 07/09/2016 at 04:56, cheese said:

Yeah. Look at Brownsville in Texas - 25 degrees north of the equator yet has a record low of -12C, and in 2011 went an entire day below freezing. It has an average high of 21C and an average low of 11C in January. In December 2004, it had a white Christmas!

The standard deviation in the US in winter is remarkably high, and as you say it's because there's no west-east mountain range to block the Arctic air. It just floods down freely. Even tropical Miami has seen sub-freezing temperatures. Nowhere else in the world has such ridiculous variations on a day to day basis. Heck, certain subtropical climates in the US can't even grown certain palm species that can grow in England because they get too many hard freezes.

But if the Himalayas did not exist the Circumpolar Vortex would be stronger without any mountain torque removing Westerly AAM from the atmosphere. This would encourage more depressions with lower general pressure across northern Canada with a persistent subtropical high across the southern USA and Mexico. This would bring stronger Westerlies in winter across temperate North America as a whole with less opportunity for frigid Arctic air to surge southwards across the continent. 

Another reason for the wide extremes across North America is the presence of the Rocky Mountains nearer the Western Sea-board of the continent. The Rocky Mountains rise extensively to 3000 metres elevation or more and thus penetrate the middle troposphere where, in winter over mid-latitudes, there are strong westerly winds. The Rocky Mountains therefore remove a lot of the global atmospheric Westerly AAM as they slow and retard the upper Westerlies that crash into them.

So big is the influence of the Rocky Mountains on the Westerlies that an almost permanent upper ridge of high-pressure is present over them. This has the effect of anchoring a ridge to the Rockies no matter how weak (or strong)  the Circumpolar Vortex is and how many ridges and troughs in these Upper Westerlies.  One effect of the Rockies causing high-pressure over it in winter is that (with an upper trough normally over eastern Canada) prevailing winds are north-westerly over the central and eastern USA and eastern Canada then and direct hits from the Arctic interior are commonplace. 

Without the Rockies, North America would have mild strong Westerlies from the North Pacific penetrating deep into the continent and winters would be milder over a wide area. Canada would be wetter, but with more snow in the north, whilst the southern USA and Mexico (under a persistent subtropical high pressure belt) would be mild and dry.

Edited September 12, 2016 by iapennell