Tropical regions can be characterized as large fields of convective clouds of all sizes. Latent heat released is
different for different precipitating systems like convective and stratiform. So we need to classify various precipitating
systems. In the present study, ground based observations of Joss-Waldvogel Disdrometer (JWD) which was installed at
Thumba (8.5°N, 76.9°E) under Ka band propagation experiment is used extensively to characterize the tropical rain. It
can be noticed that the JWD is placed at calm and noise-free places, in order to make it sensitive to smaller drops. The
JWD is a standard tool for precipitation measurements such as Drop Size Distribution (DSD), rainfall intensity, R, rain
accumulation and liquid water content, W, reflectivity factor, Z. The range of drop diameters that can be measured spans
from 0.3 to 5 mm with an accuracy of 5%. For present study Disdrometer data from June 2005 onwards are collected.
The main objective of the present study is to classify precipitation system into Convective, Transition (an intermediate
region) and stratiform. Since DSD integral parameters like rain rate (R), liquid water content (LWC), Reflectivity (Z) are
different for different precipitating systems, so we need to classify these systems. There is a dearth of raindrop Size data
and distribution models for the tropics, especially over Indian continent. Models for drop size distribution are required
for the evaluation of microwave and millimeter wave propagation effects due to rainfall. In the present paper various
DSD models namely gamma model and lognormal model with different combination of moments for observing the
characteristic features of tropical rain are studied.