Moisture + Cold Air => Snow
I just want to pre-empt the almost inevitable piece of journalistic garbage – by Christopher Booker, James Delingpole, Melanie Phillips, David Rose, or whoever – suggesting that the current snowy weather in the UK proves that global warming is not happening.
As any number of weather presenters have explained in recent days, the UK is experiencing record-breaking falls of snow this weekend because of disruption to our normal weather patterns. Once again, this abnormal weather is the result of changes in the stratosphere; with the position of the Jet Stream blocking the weather systems we would normally have coming off the Atlantic; and allowing much colder air from the European continent to sweep over us instead.
Apart from that, it is simply the case that moisture + cold air => snow: The Earth’s atmosphere today typically contains 4% more water vapour than it did 50 years ago. More moisture in a body of warm air will result in heavy rainfall; in colder air it will result in heavy snowfall. End of story. Almost.
There are just a few more pieces of the jigsaw puzzle that you might be missing:
– It is now several decades since the Earth experienced a single month of weather that was cooler than the long-term monthly average;
– Every decade since the 1970’s has been warmer than that which preceded it.
– The ratio of heat records broken to cold records broken in 2o12 was 11 to 1.
I think even my 14-yr old daughter could identify the long-term trend in that data set.