The Earths Energy Budget Flashcards
Radius of the sun?
7x10^8 metres
What conversion happens in the sun?
-Mass deficit converted into energy (5H > He)
-5(1,1)H > H(4,2) + n(1,0)
Solar radiation spectrum? Peak?
-0.15 micrometres (UV) to 4 micrometres (infra-red)
- 0.5 micrometres
What is the solar constant?
-Radiation received at top of atmosphere at mean Earth-Sun distance which is 1366 Watts per metre squared
What is solar wind and what does it cause?
Particulate flux and causes the northern lights
What does a black body do?
-Absorbs all radiation received and re-radiates it at the maximum rate possible for its radiating temperature
-e.g. the sun
What’s plancks law?
The radiation spectrum of a Black Body is determined by its radiating temperature alone.
Stefan Boltzmann law?
As temp increases the area under peak of line increases.
Wiens displacement law used for?
Determining temperature of distant stars
Wiens displacement law for the sun?
T (Temperature) =2898/0.5 T=5800K
How to calculate radiation flux?
F= o(stefan boltzmann constant) T(Temperature)^4
Black body temperature and radiation relationship?
As black body temperature decreases the radiation it gives off decreases
What does radiation received per unit area at the Earth’s surface depend on?
-The seasonal variation of the distance of the earth from the sun? - seasonal variation in day length.
-Latitude - angle of incidence - angle sun’s rays make with earth’s surface
Fact: Two times more energy received at the equator than the poles every year.
How does radiation interact with the atmosphere and the earth’s surface on way towards earth?
Scattered by particles
Reflected by clouds, aerosols, atmosphere
Reflected by surface
Absorbed by atmosphere (mainly ozone and water vapour)
Absorbed by surface
Figures for incoming solar radiation?
Scattering (particles), reflection (clouds) and absorption (principally O3, WV) - 43 % ISR
Albedo of earth’s surface - 9% ISR
48% ISR - absorbed by Earth’s surface
Cloud incoming solar reflection figures?
-Stratocumulus clouds reflect up to 80 %
-Average for all clouds is 55 %
Surface albedo solar reflection figures?
-Ranges from 2 % (calm sea) to > 80 % (fresh snow)
-Affected by angle of incidence
- Top 5 albedo reflective surfaces
Fresh snow 70-80%
Ice 20-70%
Sand desert 35-45%
Soil 10-20%
Grass 7-25%
Average planetary albedo?
30+_2%
How is albedo affected by polar regions?
-Maximum in January, minimum in July, due to larger seasonal cycle of snow and ice cover in NH
-In low latitudes, planetary albedo = 25 % (mainly cloud cover)
In polar regions, planetary albedo = 80 % (snow/ice, high angle of incidence)
Figures for more energy being absorbed at non-pole areas of the poles?
-2½ x more energy received at the top of the atmosphere at the equator than the poles over a year
-6 x more energy absorbed at the Earth’s surface at the equator than the poles over a year
Fate of radiation absorbed at earths surface: Re-radiation?
-Re-radiation from the Earth’s surface
-Absorption of greenhouse gases (water vapour, co2, ozone) leads to warming of lower atmosphere.
-Re-radiation by greenhouse gases to Earth’s surface & space.
-(net re-radiation from the Earth’s surface accounts for 39 % of absorbed solar radiation)
-
How does radiation interact with the atmosphere and the earth’s surface on way away from earth?
Lost as thermal energy
Evapotranspiration
Latent heat
Surface radiation
Emitted by atmosphere
Absorbed by surface after back radiation
Lost through atmospheric window
Fate of radiation absorbed at earths surface: Sensible heat?
-Heating of atmosphere by conduction (from Earth’s surface) and convection
-Accounts for 15 % of absorbed solar radiation
-More important in continental areas
Fate of radiation absorbed at earths surface: Latent heat?
-Evaporation (from Earth’s surface) followed by condensation in atmosphere
-Accounts for 46 % of absorbed solar radiation
-More important in oceanic areas
