On Jan 18, 9:20*am, Hugh Newbury wrote:
Mike Tullett wrote:
On Sun, 18 Jan 2009 08:29:23 +0000, Hugh Newbury wrote in


Having a look at what happened overnight, I find some surprising (to me)
movements of the pressure, temperature and humidity at about 2030 last
night. The barometer went from 995.9hPa to 998.2hPa, the temp from 8.5C
to 5.0C and the humidity from 95% to 89%, all in a matter of a few
minutes. The rain was coming down in torrents at the time too.

These figures are taken from my AWS.

Please could some kind person explain the physics/meteorology behind
these jumps.

Cold front passage?

Thanks for that. It explains the temp jump and perhaps the humidity. But
why such a sudden jump in pressure?

Sorry to be boring.

Hugh

--

Hugh Newbury

www.evershot-weather.org- Hide quoted text -

- Show quoted text -

I am doing the Open University "Understanding the Weather "course.
They say that it is difficult for forecasters to identify the position
of fronts from isobaric charts, but there is a kink in the isobars at
the fronts. They are straight lines in the warm sector, but are
curved in the rest of the cyclone/depression. If the pressure was
dropping as the cold front approached then that may explain the rapid
rise when it arrived.

HTH,

Cheers, Alastair.