APES notes atmosphere, weather
see also frog book 15.1 and 6.1
Three ways heat energy moves:
Radiation: no medium needed, e.g. light
Conduction: contact
Convection: matter in motion
Summary:
Solar radiation passes through the atmosphere
Radiation hits the earth surface, conducts to air
Hot air rises, (convection) cooler air comes in to take its place
Tilt of the earth: Basis for seasons : tilt away=winter
equinox=equal night, solstice=extremes
Equator is hottest, so greatest convection there
Three cells based on convection, cause winds
Hadley, Ferrel, Polar
Ocean currents follow the winds, clockwise in N hemisphere
Cells converge at rainy spots, diverge at deserts
Why? Clouds lift at convection spots, cooling them = rain
Dry air dropping from space = warm, dry air (deserts)
Layers: spheres bottom to top
tropo: at the surface, where all weather happens, conduction to air from surface, convection to other layers, albedo is how much energy it reflects (albus=white)
strato: higher, drier air, cooler, air travel is here, also ozone layer (stops UV)
meso: middle
thermo: hot, charged particles, also ionosphere, bounces radio waves
exo: outer
magneto; even further, deflects solar wind, protects surface (none on Mars)
Air stuff:
compress air and it heats
uncompress air (e.g. altitude) it cools
warmer air holds more water
cooler air holds less water
humidity measures how much water in how much air
relative humidity: compared to how much it can hold at that temp
absolute humidity: total amount of water
dew point: temp where water condenses
rising air condenses (rain) “adiabatic cooling” rain carries the heat away
falling air heats (deserts) “adiabatic heating” absorbs energy from the surroudings
rain shadows=dry areas after mountains
saturated 100% RH air is fog, then rain or snow
Cells:
ITCZ: at the equator, inter-tropical-convergence-zone
Hadley cell: equator to 30°N or 30°S
Ferrel cell: 30-60°
Polar cell: 60-90°
since earth is spinning, as air flows south, it also falls a bit west=tradewinds
if air flows north, it also flows a bit east=westerlies (weather describes wind from source direction)
this change of direction creates the coriolis effect
Hurricanes are low pressure systems, rising air creates a counter-clockwise flow (L on the weather maps)
High pressure systems create clockwise flow (H on the weather map)
Oceans:
winds carry surface water along, so N hemisphere has clockwise currents (cool water off CA coast)
a special current from Greenland melt flows to Hawaii, called the thermo (heat) haline (salt) current.
ENSO is a big deal: normally winds carry water off-shore of chile, bringing up food from the deep ocean (happy fisherpeeps).
El Niño reverses this, so sad fisherpeeps
La nada is no flow at all
Comments