TEMPERATURE AND TURBULENCE IN THE LOWER ATMOSPHERE

Abstract

The equation of turbulent transfer is derived from first principles, following Taylor, to focus attention on the physical nature of eddy diffusivity in the atmosphere. The equation is here extended to ?polytropic? atmospheric processes. It is shown that physical considerations imply that the eddy diffusivity is a discontinuous function of elevation through the atmosphere. The fundamental assumption is made that eddy diffusivity is a discontinuous step-function of elevation, and the equation of transfer is solved for the general case where the surface temperature is known as a function of time. The theory is tested by comparing computations with the Lindenberg observations of diurnal variations of temperature aloft. Computations and observations show good agreement at all levels, and in particular the computations agree well with the large diurnal variations observed at and above 1000 meters. Qualitative comparison is also made between theory and observations made in the lowest 100 feet of the atmosphere. Observations were taken from routine records of a Leeds and Northrup Inversion Meter at the Postgraduate School. Observation and theory show good agreement. Emphasis is placed throughout on the observed fact that eddy diffusivity is not constant and is a function of weather elements that are regularly forecast. Finally, it is shown how the results of the theory are of importance in forecasting the weather.