Solar Radiation in the Atmosphere - Short-Wave Solar Radiation in the Earth's Atmosphere - page 41

Tab l e 1 . 1 . Theprobability(%)oftheconservationofthecloudinesswiththecloudamount
equal to 1 above the European territory of the former USSR

Probability, % Duration of the existence of 1-amount cloudiness (h)

1 3 6 12 24

Winter 93 87 83 78 74

Summer 80 64 52 41 35

Tab l e 1 . 2 . The average altitudes of cloud z b (bottom) and z t (top) and geometrical thickness
∆ =

H z t − z b (km)

∆

Type of z b z t H

cloudiness Winter Summer Winter Summer Winter Summer

St 0.25 0.29 0.55 0.58 0.30 0.29

Sc 0.85 1.26 1.14 1.59 0.29 0.33

As 3.80 3.93 4.73 4.83 0.93 0.90

The detailed analysis accomplished in Harries (1996) with employing the
previous results of the observations concerning the greenhouse effect in the
global climate change has demonstrated an unfeasibility to evaluate accurately
the influence of the clouds andaerosols radiative forcingon the global warming.
The data in the topics by Feigelson (1981), Matveev (1984) andMatveev et al.
(1986) obtained as a generalization of the airborne and satellite measurements
and observations of the meteorological stations network illustrate the recur-
rence of the stratiform clouds and the average period of their conservation
above Europe that is equal to 13-15h in winter and about 5 h in summer time.
The probability of the conservation of the cloud amounts equal to 1 above the
European territory of Russia (over 10 stations) during different time intervals
is presented in Table 1.1 according to Mazin and Khrgian (1989).
As has been mentioned in the topic by Feigelson (1981) it is necessary to
understand that the obtained cloud characteristics and parameters relate to
the very given cloud in the given time period because of the strong variability
of clouds. Nevertheless, the certain recurrences of some parameters of the
stratus clouds for some geographical regions are marked. Thus, for example,
the prevailing altitude of the stratus clouds in the polar and temperate zones
is about 2 km and in the tropical zone is about 3 km.Afterthedataaveraging
oftheairborneandballoonobservationsthemosttypicalvaluesofthestratus
cloudtopandbottomaltitudeshavebeenobtainedthatTable1.2illustrates.
The stratus clouds, which are not farther than 200 km from the boundary
of an atmospheric front when it is forming and passing the atmosphere, are
called frontal clouds . The width extension of the frontal zone in central Europe
could reach 1000 km according to the satellite observations (Marchuk et al.
1986,1988). The length of this zone is about 7000 km. The cloud zones are bro-
ken to themacro cells of a hundred kilometers in length, which, in turn, consist