Module 1 Flashcards
What is the atmosphere?
Heterogeneous stratified solution of gases aerosols and liquid water
Key constituents aerosols, water, CO2, O3
Atmospheric layers in order with height
- Troposphere: 36090’ or 11 km, temp decreases, contains 75% of atmospheric mass majority of gases, liquids, aerosols and weather
2 Tropopause: layer between troposphere and stratosphere, temp typically remains constant - Stratosphere: second major layer, 11km to 50km, temp increases (-56.5 to -2°c) due to absorption of UV rays from sun by ozone in layer (21% atmospheric mass, 90% atmospheric ozone)
- Stratopause: consistent temp
- Mesosphere: temp decreases up to around 90km (Kaman line)
- Mesopause: constant temp
- Thermosphere: temp increases ≈500km
- Exosphere/ ionosphere: magnetic field interacts with solar wind. Temp decreases
Effect of surface pressure and temp on height of tropopause
Surface pressure: anti cyclone spins clockwise diverging at surface converging at altitude, if convergence outpaces divergence surface pressure will increase and tropopause height will increase and vice versa
Temperature: higher temp air expands and tropopause rises while surface pressure remains the same.
Average tropopause height, temp and pressure at equator, mid lats, and poles
Equator: height 56000’, temp -75°c, (can reach up to 66000’ with cloud tops around 75000’) 91hpa
Mid lats: 36000’ -56°c 200 hpa
Poles : 26000’ -45° 376 hpa
Sources of aerosols in atmosphere
Sea salt
Dust
Smoke
Volcanic ash
Human pollutants
Effects of aerosols
Condensation nuclei:
Freezing nuclei: ice crystals
Can reduce visibility
Create clouds and airframe icing
Effect of water vapour, CO2, and O3 on temp in atmosphere
Water vapour: requires latent heat to melt or evaporate cooling surrounds, releases that energy when condensing producing more instability and updrafts by heating surroundings, water vapour is created through evaporation or transpiration from vegetation
CO2: absorbs terrestrial radiation and releases back into atmosphere raising temps, stays in atmosphere for significant amount of time
O3: absorbs 97-99% of medium wavelength ultraviolet light from sun. Heats stratosphere causing stability and lack of weather.
Ozone creation and concentration
Created when insolation splits O2 into single atoms
Concentration measured in Dobson units
Nacreous cloud
Stratospheric
During winter
15-25km height
Only visible during night (when lit from below by recently set sun)
Consists of ice crystals and super cooled water droplets
Noticulent cloud
75-85 km
Only in high latitudes 50-65°N/s
Ice and space debris
Usually in summer
Illuminated by sun below horizon
Breaks in tropopause
Mass vertical ascent or subsidence of air renders isothermal layer impossible causing breaks in tropopause
Endothermic, exothermic, and diabatic processes
diabatic: change of state without a change in temperature
Endothermic: taking heat energy (melting, evaporation, sublimation)
Exothermic: releasing heat energy (freezing, condensation, deposition)
Specific heat
Amount of heat energy required to raise temp 1°c
Albedo
Reflective ability
More reflection means less added heat
Solar tide
Most effective in tropics
Two pressure maxima 10 am and pm
Minima 4am and pm
3-3.5 hPa difference at equator
Between tropics at 23°26’ north and south
