Storm Callum and the jet stream

It has rained all day today. The Weather Eye column in The Times newspaper carries a very effective explanation of how the jet stream winds intensified the storm. The jet stream is a narrow fast moving band of air that is roughly at the boundary between the troposphere and the stratosphere. I blogged about it in February having ascertained that trans-Atlantic aeroplanes over here were probably just into the stratosphere, 9 km up or just higher than Everest. The Polar jet stream has cold air north of it and warm air south of it. In his newspaper article, Paul Simons explains that Storm Callum crossed from the warm side to the cold side. In doing so, one side of the storm was touching the faster centre of the stream when the other side wasn't being pushed as fast. The difference made the storm spin faster, like spinning a Waltzer at the fair.