The hPa height

[kentish_sally]

Can someone explain to me the levels at which the hPa recordings for weather data is please??

i know 850 is something like 1000ft extending up to 300hPa for the JS, But could someone clarify exactly what height equates to what level (and also if possible, where it relates to aka Atmosphere, Trosophere etc...)

This would be a huge help B)

Many thanks in advance !!!!!

[johnholmes]

hi KS

1000mb is often taken as the surface; actually the 'average' sea level pressure is taken as 1013.2mb in the ICAO(International Civil Aviation Organisation).

Using standard heights, regardless of the temperature changes, allows aircraft to fly at 'set' heights without colliding into one another.

850mb=5000ft

70mb=10000ft

500mb=18000ft

400mb=24000ft

300mb=30000ft

250mb=35000ft

200mb=40000ft

is that okay?

Edited July 29, 2007 by johnholmes

[kentish_sally]

That is perfect John!!! And very much appreciated B) im guessing 70mb would be 700 though? (not to highlight mistakes, more for my own accuracy)

Massive thanks !!! a HUGE help

[johnholmes]

quite right it is 700mb not 70, finger trouble again, and I put it through spell check!

missed the bit about tropopause so will do that in a tic

we live in the Troposphere, which is where all our weather occurs.

The height of the top, called the Tropopause is dependent on how warm the Tropshere is. Thus the Trop in winter is lower than in summer. A very rough guide for the UK is

20-25000ft in winter and 35-40000ft in summer.

In the tropics its nearer 60000ft.

at the poles maybe 12000ft.

something else which often gets mentioned on the site is the jet stream.

This occurs just below the Trop and is one of the main 'movers' if you like of the weather systems, highs and lows in our climatic zone, which is the Temperate zone, sub divided into the Oceanic Temperate some call it.

Jet streams also occur in some of the other Climatic Zones around the world.

If you want fairly quick answers to most things meteorological then try this site

http://booty.org.uk/booty.weather/metindex.htm

an ex colleague and has a wealth of data about meteorology. No hype just facts.

You could also read our Guides?

Tell me when you have read all of them and every a-z on Martins' site!

Edited July 29, 2007 by johnholmes

[kentish_sally]

Thank you very much again Josh, And that site i have bookmarked for information and to read over in more detail B)

And the lowering and highering Tropopause makes also due to the expansion and contraction of heat and cold ? Would that be correct?

[johnholmes]

Thank you very much again Josh, And that site i have bookmarked for information and to read over in more detail B)

And the lowering and highering Tropopause makes also due to the expansion and contraction of heat and cold ? Would that be correct?

Josh!

very simply yes but like all things to do with the weather its rather complex.

Warm air beneath the Trop and it makes the Trop higher and vice verca

Edited July 29, 2007 by johnholmes

[kentish_sally]

@ josh - sorry, John !!! Seems both of us need to sort out that typing problem today. I blame the keyboard gremlins

[chrisbell-nottheweatherman]

Nice explanation John, thanks.

[johnholmes]

glad it helped folks

[Greeny]

quite right it is 700mb not 70, finger trouble again, and I put it through spell check!

missed the bit about tropopause so will do that in a tic

we live in the Troposphere, which is where all our weather occurs.

The height of the top, called the Tropopause is dependent on how warm the Tropshere is. Thus the Trop in winter is lower than in summer. A very rough guide for the UK is

20-25000ft in winter and 35-40000ft in summer.

In the tropics its nearer 60000ft.

at the poles maybe 12000ft.

something else which often gets mentioned on the site is the jet stream.

This occurs just below the Trop and is one of the main 'movers' if you like of the weather systems, highs and lows in our climatic zone, which is the Temperate zone, sub divided into the Oceanic Temperate some call it.

Jet streams also occur in some of the other Climatic Zones around the world.

If you want fairly quick answers to most things meteorological then try this site

http://booty.org.uk/booty.weather/metindex.htm

an ex colleague and has a wealth of data about meteorology. No hype just facts.

You could also read our Guides?

Tell me when you have read all of them and every a-z on Martins' site!

I see! I've looked at US skew T in comparison to UK Skew T and have been wondering why their cloud tops have the potential to go higher than ours certainly more often I guess especially when there is significant cape.

The majority of the time the highest saturation point on the UK skew t is 200mb then the temp ELR line higher than 200mb tends to go along at the same temp and theres no way convection can go higher than that. Also the highest cap I've observed so far when cape is present is about 350mb. where as the US Skew t like in the one illustrated the cap reaches about 160mb! Also the SALR lines seem to bulge out more than the UK SALR. So I guess their tropopause is higher than ours? Does the tropopause over the UK ever go as high as the one over the US? I haven't been reading Skew T charts for that long so not ever seen the charts in a heatwave.

[VillagePlank]

The way I think about hPa (aka millibars) is to think of it as the measure of the quantity of air above your head. The higher the hPa the more air above your head. I find it very useful to think in this way especially when thinking about some of the more mind-bending aspects of meteorology.