Paul Hyett wrote:
In uk.sci.weather on Sat, 25 Mar 2006, Tudor Hughes
wrote :
It was a gravity wave that produced the fastest pressure change I
have ever seen.. In January 1977 I was working for BP in Sunbury and
happened during a slack moment (there were many) to look at the lab
barometer. The mercury surface was visibly moving and the pressure
fell about 8 mb in 5 minutes. Not being aware of gravity waves I
thought the instrument had sprung a leak.

So what *are* gravity waves?

Not exactly sure, but perhaps it's do to with a sudden displacement of
one surface relative to another (say a sudden depression in the sealevel
caused by an underwater earthquake or something). Are tsunamis a
particular type of gravity waves? I could imagine that the passage of
fronts might cause similar effects in the upper atmosphere.

--
Jonathan Stott
Canterbury Weather: http://www.canterburyweather.co.uk/
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