L2 - Radiation balance and greenhouse Flashcards
Planck function
relates intensity of radiation from a blackbody to its wavelength (radiation curve)
Radiation
Travels as waves of photos which release energy when absorbed
Emitted energy increases to the 4th power of its blackbody temperature
Why does radiation decrease when it penetrates the atmosphere?
This is due to absorption (20%) and reflection e.g. by clouds
In what form can radiation reach the ground?
Direct radiation or diffuse radiation
Diffuse radiation
beam of radiation broken into weaker rays redirected in other direcctions by gases in the atmosphere
Albedo
measure of amount of reflected shortwave radiation (can be considered as %)
What type of radiation does the atmosphere absorb?
Longwave
What is excess radiative energy used for?
80% used for evaporation (latent heat) and 20% for rising warm air and sinking cold air (sensible heat transfer)
Inverse square law
intensity of the radiation goes down by the square of the distance from the source
There is more outgoing radiation than incoming at the poles. Does this mean they are cooling down?
No. Energy is transferred to the poles via wind, ocean currents and moisture from the tropics
Radiative forcing (RF)
The difference between:
- Incoming solar radiation
- Outgoing LW radiation
- Incoming LW radiation from stratosphere
Instantaneous radiative forcing
without temperature adjustment of the stratosphere
(Adjusted) Radiative forcing
Including temperature adjustment of stratosphere. Reduces RF due to LW flux from stratosphere to troposphere
To what extent is radiation from the lower atmosphere layers absorbed by higher layers and vice versa?
Constant absorption between layers - this is why more complex models are used
