Insolation and temperature
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This document discusses electromagnetic radiation (EMR) and its interaction with the atmosphere. It covers the following key points: 1) EMR can be described as waves with different wavelengths that determine their energy content. Shorter wavelengths like gamma rays have higher energy. 2) The atmosphere only allows certain wavelengths to pass through in "atmospheric windows" while absorbing others. Gases like oxygen, nitrogen, ozone, carbon dioxide and water vapor are significant absorbers. 3) Factors like albedo, scattering, temperature inversions, and cloud cover influence the transmission and absorption of EMR and impact atmospheric temperatures.
Insolation and temperature
- 2. 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
- 3. The wavelength (λ) of EMR is directly related to the amount of NRG in the radiation. Short (λ) (e.g. gamma rays) have a higher NRG content Long (λ) (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 λ radiation
- 5. 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 , H2 O
- 6. 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
- 8. 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
- 10. When the sun is at very low angles, virtually all the shorter λ EMR is scattered, allowing only the longer, lower NRG waves (reds) to pass through.
- 14. Of the incoming EMR, a significant portion is simply reflected back into space… Albedo
- 15. Clouds and Ice have an Albedo approaching 100%
- 16. Global albedo is not constant… but the overall average is 35%
- 17. The atmosphere is heated primarily from below… from the surface.
- 19. Adiabatic cooling and the inverse… Adiabatic warming
- 22. Note the influence of clouds… which interrupts the latitudinal patterns
- 30. 45 degrees N… halfway between equator and pole
- 32. 57.5 degrees North (same latitude as Moscow and Hudson’s Bay… semi- tropical gardens on the coast of Scotland
- 35. Temperature Inversion… warmer air slides over the cool air at the surface trapping the surface air beneath a very stable upper air mass