1. Surface Energy Budget R = - (G + H + L )
R = net solar and terrestrial radiation at the earth’s surface (+ into surface)
Absorbed solar radiation (incoming – reflected)
Incoming longwave radiation emitted by gases and clouds in the atmosphere
Outgoing longwave radiation emitted by the earth’s surface
G- storage of energy into the deep soil (- into soil)
H – heat flux into atmosphere(- into atm)
L – Latent heat flux into atmosphere ( - into atm)

2. Heat Storage Hartmann (1994) Specific heat (j/(kg K) Density (kg/m3)
Heat storage per unit volume per K
Soil inorganic
733
2600
1.9x106
1921
1300
2.5x106
Water
4182
1000
4.2x106
Air
1004
1.2
1.2x103
Hartmann (1994)

3. Soil Temperature
high intensity of solar radiation at high altitudes can result in high surface temperature
Austria- 80C humus at 2070 m; air temp at 2 m 30C
New Guinea 60C at 3480 m air temp 15C
Barry (1992)

4. Net Radiation
Whiteman (2000)

5. Surface Energy Budget
Whiteman (2000)

6. Surface Energy Budget
Whiteman (2000)

7. Solar Radiation m= 1/(sin(q) m = non-dimensional
optical depth at surface
m =1, q = 90o
m =2, q = 30o
m =4, q = 14o
When sun at 14o ,
light travelling through 4 atmospheres q m
p/ps = fraction of atmosphere above point = 1

8. Solar Radiation
M = m p/ps = non-dimensional optical depth at pressure p
At 500 mb (p/ps = .5):
for zenith angle = 14o, equivalent to path length at sea level for zenith angle of 30o
so, more radiation at higher elevation
p/ps = fraction of atmosphere above point M q

9. Solar Radiation- Ideal Atmosphere
Pressure (mb)
M=1;zenith angle= 90o
M=2; zenith angle= 30o
1000 mb
1233 W/m2
1136 W/m2
500 mb
1288 W/m2
1227 W/m2
Diff = 55 W/m2
91 W/m2

10. Barry (1992)
Solar radiation reduced in lower atmosphere by:
--absorption of radiation by water vapor
-- Mie scattering by aerosols

11. Absorbed Solar Radiation
Absorbed solar radiation depends strongly on albedo: Abs Solar = Solar (1 – a)
Snow cover reflects solar radiation and diminishes absorbed solar radiation
Annually, snow cover at high elevation later in season than in valleys tends to cause absorbed solar radiation to diminish with elevation
Whiteman (2000)

12. Incoming Longwave Radiation
Iijima and Shinoda (2002)

13. Outgoing Infrared Radiation
Stefan-Boltzmann Law: IR = esT4
As elevation increases:
temperature decreases, IR radiation decreases
Optical thickness of atmosphere decreases (less greenhouse gases, including water vapor), atmospheric transparency to outgoing radiation increases, more IR escapes
Emissivity (e) of snow and ice is high
Whiteman (2000)

14. Infrared Radiation: December, Austrian Alps
Altitude (m)
Bare ground W/m2
Snow cover W/m2
200
289
301
1000
270
287
2000
255
274
3000
240
Barry (1992)

15. Net Radiation
Net Radiation = Absorbed solar radiation + downwelling IR – IR
Effect of altitude on net radiation is variable and depends most strongly on decrease with height of absorbed solar radiation
Barry (1992)

16. Peter Sinks
Clements (2000)

17. Radiation Budget on Slope
downwelling IR
solar IR
Temperature
slope
Temperature ground

18. Variations in sunrise time
Whiteman (2000)

19. Influence of aspect (orientation)
Barry (1992)

20. Influence of aspect (orientation)
Barry (1992)

21. Influence of slope angle
Barry (1992)

22. Inclination angle, valley orientation, season
South – north West - east
Inclination angle, valley orientation, season
Whiteman (2000)

23. Microclimates Small topographic irregularities
Differences in slope angle and aspect
Types (Turner 1980)
Sunny windward slope (high radiation; high wind)
Sunny lee slope (high radiation; low wind)
Shaded windward
Shaded lee

24. Microclimates
Barry (1992)