Insolation and Temperature Chapter 4

Electromagnetic Radiation (EMR) can be described as waves. Note the generation of a magnetic field at right angles to an electrical field and both are perpendicular to the direction of EMR propagation http://micro.magnet.fsu.edu/primer/java/electromagnetic/index.html  

The wavelength () of EMR is directly related to the amount of NRG in the radiation. Short () (e.g. gamma rays) have a higher NRG content Long () (e.g. thermal or microwave (Radio) have a lower NRG content As the velocity of the propagation of EMR (the speed of light) is believed to be a constant (c) The number of waves to pass a single point in a given period (the frequency, v) is much higher for shorter  radiation

Atmospheric Windows Some EMR passes through the atmosphere with no interference (an ‘atmospheric window’ Some EMR is absorbed (or blocked) by components in the atmosphere The most significant absorbers of EMR in the atmosphere are O2 , N2, O3, CO2, H2O  

Gamma radiation, X-rays, and UV radiation absorbed in the upper atmosphere  Water vapor and Carbon Dioxide absorb portions of the EM spectrum in the thermal portions of the spectrum

Atmospheric scattering: (skylight or haze) Rayleigh scatter (molecular scatter) primary factor in upper atmosphere (why the sky is blue) Mie scatter (non-molecular scattering, water/ice/salt/smoke) primarly in lower atmosphere

When the sun is at very low angles, virtually all the shorter  EMR is scattered, allowing only the longer, lower NRG waves (reds) to pass through.

Of the incoming EMR, a significant portion is simply reflected back into space… Albedo

Clouds and Ice have an Albedo approaching 100%

Global albedo is not constant… but the overall average is 35%

The atmosphere is heated primarily from below… from the surface.

Adiabatic cooling and the inverse… Adiabatic warming

Note the influence of clouds… which interrupts the latitudinal patterns

45 degrees N… halfway between equator and pole

57.5 degrees North (same latitude as Moscow and Hudson’s Bay… semi-tropical gardens on the coast of Scotland

Normal Atmospheric Conditions…

Temperature Inversion… warmer air slides over the cool air at the surface trapping the surface air beneath a very stable upper air mass