Question

How does Radiative Warming create Foehn Winds?

Answer 1

First we should know what is Foehn effect-

It is the process which makes one side of a mountain much warmer than the other side of mountain.

The manner with which the winds hit the mountains causes this effect to occur like when air moves up the mountain and ,as pressure drops air cools rapidly forming clouds resulting in rain on the windward side and when this air moves towards leewards side it is much warmer due to the loss in moisture and gain in heat.

As this dried air is moved on leeward side resulting in no cloud formation hence, more clear sky and warmer temperature conditions occur due to more sunlight on leeward side producing more heat. ALso when air travels down on the leeward side of mountains then the air heats up as it is under greater atmospheric pressure which creates very strong dry and warm winds.This is also known as Rainshadow effect.

RADIATIVE WARMING is one of the contributing factor which adds warming on the leeward side-

Radiative warming = constant flow of heat from sunlight - reflected heat energy + heat radiated from earth after heating.

if radiative warming is positive then heating will take place.

Example-

If you have a kettle full of water, which is at room temperature. That means everything is at equilibrium, and nothing will change except as small random variations. But light a fire under that kettle, and suddenly there will be more energy flowing into that water than radiating out, and the water is going to start getting hotter.

In short, radiative forcing is a direct measure of the amount that the Earth’s energy budget is out of balance.

Therefore more is the inflow and accumulation of radiation more will be the heating of the atmosphere resulting in Foehn effect.

For the Earth’s climate system, it turns out that the level where this imbalance can most meaningfully be measured is the boundary between the troposphere (the lowest level of the atmosphere) and the stratosphere (the very thin upper layer).

Radiative warming is measured in watts per square meter of surface.