Temperature fluctuations inside a cloud-laden airstream flowing over a hill station

Abstract

Observations of temperature in a cloud-laden monsoon airstream at a height of 12 m above ground at a hill station, Mahabaleshwar (elevation 1390 m asl), were obtained for ten hours using a linearised thermistor (YSI Part 44202) as a temperature sensor, and analysed. It was found that the frequency distributions of temperatures were multimodal. The horizontal temperature gradients in the air stream were symmetrically distributed. The temperature spectra in the frequency range (0.001 to 0.1 Hz) studied can be classified into a lower frequency regime and a higher frequency regime separated approximately at the frequency 0.01 Hz or the wave number 3 km⁻¹. The spectra in the higher range conform to Kolmogorov's power law for the inertial subrange and those in the lower range exhibit a steeper negative slope of the order of -1.3. There is very little variation of air temperature associated with rainfall intensities greater than 4 mm hr⁻¹; for lower intensities, the smaller the intensity, the greater the variation.