SATELLITE PHOTOGRAPHS OF CONVECTIVE CLOUDS AND THEIR RELATION TO THE VERTICAL WIND SHEAR

Abstract

Several TIROS photographs of cumulonimbus clouds and thunderstorms over the Florida area are compared with synoptic surface and upper-wind data. The orientations of the cirrus anvils of well-developed clouds generally show good directional agreement with the existing vertical wind shears between the lower and upper troposphere. Limited evidence also suggests that the length and character of the anvils may sometimes be used as qualitative indicators of shear magnitude, the longer and more pronounced anvils being positively correlated with stronger vertical shear. In agreement with earlier studies, it is found that cumulonimbus clouds often appear as relatively small or medium-sized, irregular, bright masses in TIROS pictures, hence such clouds often can be tentatively identified from their picture appearance alone. Such identification is still largely a subjective procedure. The anvils of well-developed cumulonimbi, when attached to the parent cloud, are rather distinctive and are an aid to identification. A few TIROS pictures of the Florida area under relatively clear conditions are shown for comparative purposes. The problems arising from specular reflection and from variations in overall photo appearance resulting from changing camera angle are briefly discussed.