geog 402 - university of hawaiʻi
Post on 15-Mar-2022
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Slope – Aspect – Elevation Mountain Influences on Microclimate
• Elevation – temperature – humidity – cloud cover (radiation) – fog – Rainfall
• Slope and aspect (azimuth) – radiation balance – water drainage
Direct beam radiation on a slope
( ) )cos()sin()sin()cos()cos(cos slopesun AAZsZsi −+= Eq. 6.2
I = incident direct beam radiation
S↓= normal incidence radiation
i = incidence angle
s = slope angle
Z = solar zenith angle
Asun = azimuth of the Sun
Aslope = azimuth of the slope
)cos(ZSI ↓= Eq. 6.1
On a horizontal surface:
On a sloping surface:
Diffuse radiation on a slope
( )2cos1 s
sky+
=ψ
ψsky = fraction of hemisphere composed of sky
ψ terrain = fraction of hemisphere composed of sky
Eq. 6.4
Fraction of sky seen:
Fraction of hemisphere composed of terrain:
skyterrain ψψ −=1
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