Abstract
The field observation shows that the leaf surface of the vegetation top iscooled to the lowest temperature in the vegetation by the sky radiation, while the air temperature inside the vegetation stays warmer during the clear night. The leaf surface of the vegetation top is refrigerated by the sky radiation, then the air next to the vegetation top is got cooled by the sensible heat exchange from the air to the leaf surfaces. Because of the observation errors on the leaf surface temperature, the calculated results have not completely agreed with the field experiments. The calculation results shows that the atmospheric air is easily got cooled if the leaf area index is large in the tall tree crowns.
