Net radiation

flux.

denotes optical depth for homogeneous radiation flux

ε is a coefficient depending on the Sun altitude.

NR depends only slightly on optical depth of the atmosphere

That is why we can adopt value as a constant

Kondratiev’s formula

altitude (ho) and atmospheric transparency (we’ll denote it be the letter “c”).
C=0,27 corresponds to the highest transparency; c=0,91 – to the lowest one.

can vary significantly. Global amplitude=215 w/m².

Cloudless atmosphere absorbs and diffuses 20% incoming SR.

Cloudiness further diminishes about 25% of SR

The rest 55% reaches the ground surface

is the net radiation flux in cloudless atmosphere,
n is cloud amount in decimal fractions,
“f”, “a”, “b” are empirical coefficients.

These coefficients depend on latitudes and type of underlying surface (land or sea).

For the land surface the coefficients are presented in the table on the page 1 of the Lecture Note #5.

e is water vapor partial pressure in hPa, d is deficit of the water vapor pressure in hPa.

Qn is net radiation at the ground surface, Q° is the solar radiation flux at the top of the atmosphere.

nt is amount of the total cloudiness, nl is low cloudiness amount.

In case of no information on humidity