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It's a strange climate indeed. So you have a low latitude southern location with very cold Pacific water on the west side and the east are gigantic mountains (Andes) blocking the more extreme and humid air from the Atlantic. So the cool marine air encounters the warmer land mass air and the warmer air is able to absorb the marine air which isn't holding so much humidity due to the colder pacific waters....the air surface temps at Lima never drop down low enough to drop the moisture in the air.
I worked in Peru for 16 months and every time I went to Lima, the climate was comfortable but almost invariably cloudy but not as much density of clouds like you see here in Seattle through much of the winter. Where I worked in Arequipa, the climate was very stable and comfortable with very little rain but much sun.
There are three elements to take into account:
1) Low latitude
2) A cold current
3) The Andes
1) As Lima is located at merely 12ºS, it's an area where sunshine is very strong, then temperatures throughout the air column over the city are overall high (compared to the air column at higher latitudes).
2) However, there is a cold current there whose waters are much colder than what is expected in such area, so the much warmer and somewhat humid surface air cools down and approaches the condensation, so advection fog and low stratus clouds are formed. But as I said, the air column is relatively hot due to the low latitude, so the most superficial layer keeps abnormally cooler than the immediately higher layers, what results in an almost perpetual thermal inversion. And you know, hot air is lighter than cool air and rises, which if humid enough forms convective clouds that ultimately causes rain. It can't happen in Lima due to the thermal inversion (bar very unusual situations, obviously).
3) Finally, we have the Andes range, which acts as a barrier prevent any warm Amazonian air mass from reaching the Peruvian coast, whereas it enhances the formation of stratus clouds by forcing the rising of the maritime air that reaches the coast via sea breeze.
So, Lima is condemned to live with advective fog, stratus clouds lying under 500/600 metres above the sea level and frequent garua (very light rain), but almost never getting proper rain; let alone thunderstorms.
If there was a bulding as tall as the Burj Khalifa in Lima, the highest floors would break over the sheet of clouds and always see the sun as in Arequipa. They would also be warmer than the surface
Location: Live:Downtown Phoenix, AZ/Work:Greater Los Angeles, CA
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Quote:
Originally Posted by Mhc1985
There are three elements to take into account:
1) Low latitude
2) A cold current
3) The Andes
1) As Lima is located at merely 12ºS, it's an area where sunshine is very strong, then temperatures throughout the air column over the city are overall high (compared to the air column at higher latitudes).
2) However, there is a cold current there whose waters are much colder than what is expected in such area, so the much warmer and somewhat humid surface air cools down and approaches the condensation, so advection fog and low stratus clouds are formed. But as I said, the air column is relatively hot due to the low latitude, so the most superficial layer keeps abnormally cooler than the immediately higher layers, what results in an almost perpetual thermal inversion. And you know, hot air is lighter than cool air and rises, which if humid enough forms convective clouds that ultimately causes rain. It can't happen in Lima due to the thermal inversion (bar very unusual situations, obviously).
3) Finally, we have the Andes range, which acts as a barrier prevent any warm Amazonian air mass from reaching the Peruvian coast, whereas it enhances the formation of stratus clouds by forcing the rising of the maritime air that reaches the coast via sea breeze.
So, Lima is condemned to live with advective fog, stratus clouds lying under 500/600 metres above the sea level and frequent garua (very light rain), but almost never getting proper rain; let alone thunderstorms.
If there was a bulding as tall as the Burj Khalifa in Lima, the highest floors would break over the sheet of clouds and always see the sun as in Arequipa. They would also be warmer than the surface
It's the same thing that happens to coastal California in May and June (May Gray/June Gloom). Pacific heats much more slowly than the deserts inland, and lower elevations heat slower than the mountains above the marine layer, traps cooler air at the surface, creating cloudy conditions, yet stable
Less sunshine than the east coast of Scotland and less sunshine in winter than we have in Glasgow, despite much longer days. That is impressive.
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