So Where Do Hadley Cells Fit In?

[smich]

Hi again everyone! Not posted for a while - too busy mainly.

But hey, I've been thinking...(Many of you may have heard it ) what with teleconnections, jetstreams, low and high pressure etc etc etc it all paints a pretty chaotic picture.

However I remember reading about Hadley cells - these are "cycles" of air that warm near the equator and rise. The colder air from the north is sucked in and the warmer high altitude air is forced northwards. As is reaches the more northerly latitudes it cools and sinks again - simple really, and about as certain as weather can get!

But it doesn't seem to be mentioned in discussions much - does it still have a place in "modern theory"?

Whaddya all reckon?

Smich

[Dawlish]

Hi again everyone! Not posted for a while - too busy mainly.

But hey, I've been thinking...(Many of you may have heard it ) what with teleconnections, jetstreams, low and high pressure etc etc etc it all paints a pretty chaotic picture.

However I remember reading about Hadley cells - these are "cycles" of air that warm near the equator and rise. The colder air from the north is sucked in and the warmer high altitude air is forced northwards. As is reaches the more northerly latitudes it cools and sinks again - simple really, and about as certain as weather can get!

But it doesn't seem to be mentioned in discussions much - does it still have a place in "modern theory"?

Whaddya all reckon?

Smich

It does have a place, totally, smich; nothing has changed, but the Hadley cell sinks around 30 degrees N and S of the equator. As such it doesn't affect our weather directly. The sinking creates the great deserts of the world (at sea, they are called the "horse latitudes") as upper level converegeance cases air to sink and warm, creating vast anticyclones at the surface.

I feel that things have changed, in the last 25 years, in our latitudes, though, and heat is now more likely to escape from these areas and track away from the convergeance zones towards more temperate areas.

Hope this helps, Paul

Edited July 25, 2006 by Dawlish

[Gray-Wolf]

The sinking creates the great deserts of the world (at sea, they are called the "horse latitudes") as upper level converegeance cases air to sink and warm, creating vast anticyclones at the surface.

Called the 'Horse Latitudes as the ocean used to be full of horse carcasses from ships transporting horses to the new world that became becalmed and the nags perished due to heat/dehydration. Some ships logged dead horses for days on end as they (slowly) worked through the 'Horse Latitudes'. (yuck).

[smich]

Hi Guys

I hadn't realised that the cells cover such a narrow band close to the equator - just assumed they covered the earth up/down to the poles! And I reckon that's right about them "expanding" somewhat as as warmer air escapes. With a mechanism as simple and sure as Hadley Cells, it must be a good way to measure the impact of global warming...

"Horse latitudes" - never heard the term before - and nice to know the origin of the phrase too! Thanks GW

Smich

Edited July 26, 2006 by smich

[Dawlish]

Hi Guys

I hadn't realised that the cells cover such a narrow band close to the equator - just assumed they covered the earth up/down to the poles! And I reckon that's right about them "expanding" somewhat as as warmer air escapes. With a mechanism as simple and sure as Hadley Cells, it must be a good way to measure the impact of global warming...

"Horse latitudes" - never heard the term before - and nice to know the origin of the phrase too! Thanks GW

Smich

There's 3 classic circulation cells from the equator out to the poles; the Hadley cell, Ferrel cell and Polar cell. Have a look here, smitch:

http://www.newmediastudio.org/DataDiscover...rade_Winds.html

Paul

PS The propensity of more summer heat "escaping" from the desert areas, over time, as the world warms is only a theory of mine; I have nothing to back that up.

Edited July 26, 2006 by Dawlish

[parmenides3]

Thanks, dawlish: another helpful post. So: the Azores high and the Iceland Low which form the NAO are the Atlantic's expression of the subtropical high and the subpolar low pressure areas, then? Makes sense.

[johnholmes]

hi

You have been given your answers pretty well, there are many sites for you to browse over if you have msn or google, just type in ferrel cells, hadley cells etc.

This is one I came across

http://www.weather-climate.org.uk/12.php

I have not checked the site out but the first few lines look fine to me so I would imagine its a good site. It seems to explain how the various climatic zones are set up around the world so could be worth a read for many people

enjoy

John