On the structure of the trade wind moist layer

Abstract

Comparison of the lower trade-wind air under conditions of strong versus weak circulation is continued, Moisture and thermal structure and transports from the top of the mixed layer up to the trade-wind inversion are investigated. Much less difference is found at those levels between weak and strong circulation period than was found in the lowest or mixed layer. It is shown that the development of trade cumulus convection is dependent primarily upon conditions below cloud while for immense cumulonimbus build-ups convergence in the large-scale flow appears to be necessary. A physical model of the moist layer is constructed which describes the interaction of cloud populations with their surroundings, It shows how the cloud groups, though they average level-for-level both virtually and potentially colder than the clear, are thermally direct circulations providing heat and moisture to the trade. The model is built up from numerical calculations based primarily upon the aircraft soundings made in the undisturbed trade near Puerto Rico in April 1946 and March - April, 1953.