The Barometer guys have just published a new episode on snow. It’s another good one. I’m starting to really miss being involved with the show!
In this episode they talk for a bit about how snow forms and it reminded me of this really nice video showing the melting layer in a precipitating cloud (click to play):
In the higher levels of the cloud (where it’s really cold) the precipitation starts out as ice and snow, which falls much slower than rain. But if you look closely at about 2 km you can see the point where the ice and snow melts and becomes rain – this is known as the melting layer. The rains falls much quicker than the snow above.
It snows at the ground when the lower levels of the atmosphere are particularly cold and so the snow doesn’t melt. This is what’s been happening recently.
Andy Russell's weather and climate blog 
January 6, 2011 at 4:07 pm |
[…] Why has this winter been so cold in Europe? By andyrussell I’ve written a couple of posts recently looking at the cold UK weather in context and how snow forms. […]
June 19, 2012 at 12:24 am |
so why does it snow??????????????????
June 19, 2012 at 8:38 am |
Well, there are lots of different answers to that question. The one that relates to video is that the lower atmosphere needs to be cold enough for the snow not to melt. If it melts, as it does in the video, then we get rain. If it doesn’t melt, then it snows!
A more difficult question to answer is: why do snowflakes form? There’s a nice wiki page for that.