In answer to
Helol, I did a little Googling and came up with this from Flying the Hump by Otha C.Spencer.
The world’s most violent weather comes into Asia because it is the meeting place of three turbulent air masses: low pressure from the west moves along the main range of the Himalaya between Tibet and India to the Hump, where warm, wet high pressure systems from the Bay of Bengal clash with frigid low pressure from Siberia. The polar vonex, and the heat rising from the jungles of Burma, intensify the weather movement.
I also seem to recall a pilot apologising for the turbulence over the Bay of Bengal as we came into Singers once (it wasn't his fault!). But he said it was caused by air swirling up from the equator meeting the air coming from the Himalayas -- which would seem to gel with the explanation above.