1 Nitrogen 78 Oxygen 21 2 Pressure decreases exponentially with altitude height The reason for this is because gravity exerts hydrostatic pressure and that air is compressible Imagine a diagram a b 50 OF ATMOSPHERIC MASS IS WITHIN 5 5KM 3 Layers of atmosphere as defined by temperature a Troposphere b Stratosphere i Temperature decreases with height ii All living things are in this layer i Temperature increases with height ii Ozone absorbs radiation increased temperature iii Few clouds c Mesosphere d Thermosphere i Temperature decreases with height ii Nothing interesting happens here i Temperature increases with height ii Molecules heat up because of low density and solar radiation 1 O2 and N2 e Exosphere 4 Heat transfer mechanisms a Conduction i Lighter particles can escape to outer space i LEAST IMPORTANT IN THE ATMOSPHERE ii VERY IMPORTANT ON THE SURFACE iii Transfer of heat energy from one medium to another with temperature gradient where the change in temperature cannot equal 0 Kelvin iv No transport of mass v Air is an extremely poor conductor b Convection i Transfer of energy by the movement of air ii Transport of mass Gas particles iii Imagine it as a cyclic process where air particles are constantly moving and transferring energy from one particle to another iv Weak over cool surfaces because the air parcel isn t warmer than the surrounding environment v EFFIECIENT WAY TO TRANSFER HEAT IN THE ATMOSPHERE i Horizontal movement of energy gases and particles ii Essentially it s the movement of energy using the wind c Advection d Radiation 5 Latent Heat a Heat required to change a substance from one state to another b c Important source of atmospheric energy Increasing latent heat Ice to water Melting i ii Water to gas Evaporation d Heat energy released to the environment i Vapor to liquid Condensation ii Liquid to solid Freezing e Water vapor is important i Greenhouse gas ii Transports latent heat into the atmosphere iii Condensation leads to heating the air 1 It releases energy into the atmosphere 6 Radiation a Transfer of energy without a medium i Wavelength ii Frequency WAVES emission is 1 Total length between the peaks curves and troughs 1 Total number of peaks or troughs iii SHORTER WAVELENGTHS CARRY MORE ENERGY THAN LONGER 1 Imagine long wavelengths like radio waves Imagine short wavelengths as X ray or ultraviolet waves iv The higher the temperature the lower the peak blackbody v RADIATION INCREASES TO THE 4th POWER OF IT S TEMPERATURE 7 Solar Radiation Terrestrial radiation a Solar Radiation i Is scattered and reflected by the atmosphere clouds and earth s surface ii Heats the earth s surface iii Creates an average albedo of 30 1 fraction of solar energy shortwave radiation reflected from the Earth back into space iv Heats the earth s surface b Terrestrial Radiation i Outgoing radiation from the earth in the form of long waves ii Heats up the atmosphere 8 Chemical compounds which interact with solar and terrestrial radiation 9 Greenhouse Effect a Earth s atmosphere absorbs and emit infrared radiation that keeps lower atmosphere warm b Water vapor H2O Carbon Dioxide CO2 i Strong absorbers and emitters of infrared radiation ii selectively absorb and emit infrared radiation thereby keeping the earth s average surface temperature warmer than it would be otherwise 10 Reasons for seasons relationship with solar intensity a The seasons defined by mean temperature variations are caused by the earth being tilted on its axis as it revolves around the sun This causes seasonal variations in both the length of daylight and the intensity of sunlight that reaches the top of the atmosphere b Earth is inclined on its axis 23 5 11 Daily and seasonal temperature variations a Daily i Solar radiation heats the atmosphere from below by soil conduction and atmospheric convection ii Ground cools adjacent air layer by soil conduction Heat transfer from air above is slow due to poor thermal conductivity of air iii Formation of a temperature inversion that may be diminished 12 Daytime warming and nighttime cooling processes typical T profiles close by winds b Seasonal i to the ground a Daytime Warming b Nighttime Cooling i Solar radiation heats the atmosphere from below ii Winds create a forced convection of vertical mixing that diminishes steep temperature gradients iii During the day the surface of the earth and the air above it will continue to warm as long as incoming energy mainly sunlight exceeds outgoing heat energy from the surface i Ground cools adjacent air layer by soil conduction Heat transfer from air above is slow due to poor thermal conductivity of air ii Winds create a forced convection of vertical mixing that diminishes steep temperature gradients iii During the night the earth s surface cools by giving up more infrared radiation than it receives a process called radiation cooling