Tropospheric levels

[crimsone]

After searching for definitions, it seems that I can only find half a story from the AMS glossary.

We always hear how something is an "upper level low" or a "mid level trough", but it seems that a description is evasive. So far I've managed to find out that the upperlevel is usually considered to be anything above 850 hPa, that the low level is up to about 6000 feet, and the mid level is everything inbetween.

The thing is, these are approximates. How exactly are these levels defined? What values are they defined as?

Are there any characteristics specific to each level? I mean, I know the earths atmospheric flow is a general trend from west to east, but is this true of all three levels? What's the difference (for example) between a mid level and low level trough?

Is there anybody that can offer a definitive description of these levels, or is it something that's just approximated as we go along?

[johnholmes]

sorry this is wrong

east to west

the general flow in the north and southern henisphere is West to East.

pm me and I'll try and explain any points you want to raise tomorrow.

John

[crimsone]

Ah. sorry. That's just my mind going screwy and coming out with words in the wrong order. lol.

I shall PM tlater though - thanks

[pottyprof]

Ah. sorry. That's just my mind going screwy and coming out with words in the wrong order. lol.

I shall PM tlater though - thanks

nowt new there then... :lol:

[BrickFielder]

There is no specific answer. Upper levels are usually up around the jetstream at above 350hPa. 500hPa is often considered a mid level. 850hPa is getting toward low level. 700hPa may be mid or low level depending on your definition.

[crimsone]

hankyou very much Hemlock and John - your help is very much appreciated