Field observations and laboratory simulation of the lifted temperature minimum

Abstract

The present work is concerned with a peculiar vertical temperature distribution that sometimes develops over the ground during calm and clear nights. After sun- set, typically an inversion pro¯le is expected to form, in which a minimum in the vertical temperature pro¯le occurs at the ground. However, on calm and clear nights, a temperature pro¯le often develops, where the minimum of temperature occurs a few decimeters above the ground. This phenomenon, ¯rst reported by the Indian agro-meteorologist Ramdas in 1932, is identi¯ed by various names like `The Lifted Temperature Minimum', `The Elevated Temperature Minimum', `The Ram- das E®ect', etc. The lifted minimum is characterized by its height and intensity, the height of the minimum simply being the height above the ground at which the minimum occurs, while the intensity of the minimum is the di®erence between the ground temperature and the minimum temperature.