Ratiation 2 Flashcards
What are the three heat transfer mechanisms?
Conduction - transfer of heat between objects by direct contact by molecular collisions. Due to temperature difference.
Convection - transfer of heat through liquid/air by actual flow of matter. Due to density difference.
Radiation - transfer of heat without any physical contact between objects. Objects emit radiation when temperature is above 0 K.
What is latent heat?
Energy required to convert from one state to another without a change in temperature
What is Rayleigh Scattering?
Small molecules such as nitrogen are able to scatter away very small wavelengths (e.g. blue visible light)
What is the Earth’s energy budget?
Incoming solar radiation - 340 Wm (100%)
Solar radiation reflected - (30%)
Solar radiation absorbed by atmosphere - (19%)
Solar radiation absorbed by land - (51%)
Solar radiation emitted back to space - (70%)
Radiative heating in atmosphere - 434 Wm
Radiative cooling in atmosphere - 532 Wm
Thermal heating and latent heat release - 97 Wm
Net absorption of Earth’s surface - 1 Wm
What is the radiative heating/cooling of the troposphere and the stratophere/mesosphere?
Troposphere - water vapour responsible for both short-wave and long-wave absorption (HEATING), and also emission of long-wave (infrared) radiation (COOLING). There is a net radiative cooling.
Stratosphere/Mesosphere - ozone responsible for heating and cooling. There is a net radiative balance.
What is albedo?
What is surface albedo?
What is cloud albedo? What is the different effect of high cirrus clouds and low cumulus-stratus clouds?
Albedo is the proportion of incident radiation that is reflected by an object.
Surface albedo is scattering from a surface.
Ice/snow - high albedo (0.9)
Deserts - high albedo (0.8 - 0.9)
Ocean/forest - low albedo (0.1)
Cloud albedo is the scattering by the clouds. Clouds reflect solar radiation (cooling) and absorb extraterrestrial radiation (heating).
High clouds - net radiative heating
Low clouds - net radiative cooling
