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      https://www.ias.ac.in/article/fulltext/jess/108/04/0287-0295

    • Keywords

       

      Layered clouds; convective clouds; visible clouds; sub-visible clouds; inertio-gravity waves; Brunt-Vaisala oscillations; Kelvin-Helmholtz waves; turbulence; MST radar reflectivity

    • Abstract

       

      Contrary to the prevalent belief that tropical region is characterized by convective clouds rather than by layer clouds, we have suggested that deep convective clouds occur on meso-scale, but layer clouds occur on larger synoptic-scale with a relatively small region of deep convective clouds. Sustenance of deep convective clouds is inhibited by the presence of inertio-gravity waves, which have alternating layers of upward and downward motion in the vertical. We have also shown that inertio-gravity waves generate regions of relatively strong horizontal velocity, vertically separated by layers of relatively weak horizontal velocity. Layers of strong horizontal velocity are created by inertio-gravity wave system through convergence of vertical flux of horizontal momentum. We have also suggested that horizontal convergence/divergence of moisture flux is generated by inertio-gravity waves, giving rise to vertically alternating layers of high/low humidity, and visible or sub-visible clouds. Layers of high humidity become layers of strong radar reflectivity at frequency of 53 MHz at which MST Radar at Gadanki, near Tirupati, India, operates. These observations, more than 2,50,000 in number, for vertical grid points, spread over all the months of the year, have helped us, among other observations, to arrive at these conclusions. Further, the analysis suggests that the main source of strong MST radar reflectivity is not mechanical turbulence as is commonly believed.

    • Author Affiliations

       

      M K Rama Varma Raja1 G C Asnani1 P S Salvekar1 A R Jain2 D Narayana Rao3 S Venkoba Rao3 P Kishore3 M Hareesh3

      1. Indian Institute of Tropical Meteorology, Dr Homi Bhabha Road, Pune - 411 008, India
      2. Department of Space, National MST Radar Facility, P. O. Box 123, Tirupati - 517 502, India
      3. Department of Physics, Sri Venkateswara University, Tirupati - 517 502, India
    • Dates

       
  • Journal of Earth System Science | News

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