Western Disturbances – Structure

Abstract

The Indian subcontinent is characterized by its large spatial expanse along with heterogeneity and the variability of land use and land cover. These characteristics of India cause an extraordinary variety of climatic regimes over the various parts of the country. Western disturbances (WDs) are one of the many varied types of weather systems affecting Indian climate. The WD phenomenon causes precipitation over the Indian region mostly during the winter period and mostly over the northern part. WDs are a type of extra-tropical cyclone, which have mid-latitude frontal characteristics, that migrate eastward embedded in the subtropical westerly jet stream. But WDs are not just a typical extra-tropical cyclone, but they also have unique characteristics and dynamics. This chapter provides a detailed introduction to the topic and discusses the origin, migration, large-scale flow linkages and structure of WDs.