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
What can optical depth also be called?
Bulk emission level
What is the zonal heat transfer gradient from net radiation?
-Zonal gradient in long-wave emission from Earth’s surface is less than gradient in short-wave absorption.
-Absorption>emission at 40 degrees North and South.
-Emision<absorption poleward of 40 degrees north and south.
Advection?
Atmospheric and oceanic circulation?
True or False? Equilibrium is achieved through advection of heat from low to high latitudes? Facts?
True.
-Without advection equatorial temperatures would increase by 14 degrees; polar temperatures would decrease by 25 degrees
-Wind-driven surface currents account for 30 % of poleward heat transport (sensible & latent heat transfer to atmosphere at higher latitudes)
Climate features of atmospheric circulation?
-Western coastal areas wetter than eastern counterparts
-Continental interiors relatively dry and greater seasonal temperature fluctuations than at margins (‘continentality’)
How is the movement of air affected by Coriolis force associated with Earth’s rotation?
-Deflection of movement to right in Northern Hemisphere and left in Southern Hemisphere
What is a Hadley circulation at tropical and subtropical regions?
-In the intertropical convergence zone.
-Heating greatest over equator causes ascending air in convergent flow which creates zone of low pressure at surface.
-Air becomes aloft in divergent flow and moves to each pole where it becomes dry air and cools and sinks at 30 degrees north and south (Horse latitudes).
-Then air returns to flow at surface with NE trade in the North and SE trade in the South and they again converge at the intertropical convergence zone.
Describe climate of the intertropical convergence zone? (Lower latitude of earth)
Thick cloud, heavy rainfall, little seasonal temperature change.
Describe climate of horse latitudes (30 degrees North and South) ?
Light and variable winds, very dry.
What’s a polar cell? Features? (Upper latitude of earth)
-Weak polar cell driven by sinking air at poles
- Occurs above 60 degrees (angle)
-Surface flow direction of equator = polar easterlies
-Climates cold and often arid.
Describe climate of mid latitude degrees of earth?
-Westerly surface and upper flows (‘mid latitude westerlies’).
- Associated with planetary (Rossby) waves.
-Number, position and amplitude of Rossby waves variable which leads to wandering high and low pressure systems.
-Warm and cold fronts facilitate heat exchange.
