Unprecedented, widespread, and devastating hailstorms occurred during February and March 2014 over north peninsular India (study area). A diagnostic study has been carried out to understand the causes for the same. Over the study area the atmosphere was convectively unstable due to the incursion of warm and moist air from Bay of Bengal and Arabian Sea which was overlaid by cold and dry midlatitude westerlies caused due to the unusual upper oceanic heat content of the Pacific Ocean.

Ground and satellite based measurements of spectral optical properties of aerosols have been carried out at Dehradun (DDN) in the Indo-Gangetic Plain (IGP) and Kavaratti (KVT) at Lakshadweep in southern Arabian Sea during pre-monsoon season (March–May) 2012. The measurements illustrate distinct seasonal impact on aerosol properties with maximum dust loading during May in conjunction with anthropogenic aerosols over DDN and marine aerosols over KVT.

Western disturbances have a long history of climatological, synoptic and satellite observations based studies. In present study an attempt has been made to understand the different aspects of western disturbances like movement, associated convection, induce systems and associated weather. The western disturbances (WDs) during post monsoon and winter season have been selected for the study as they are mainly responsible for precipitation over western Himalayan region and adjoining plains of northwest India.

In the last decade, the northern Arabian Sea has witnessed a radical shift in the composition of winter phytoplankton blooms, which previously comprised mainly of diatoms, the unicellular, siliceous photosynthetic organisms favoured by nutrient-enriched waters from convective mixing. These trophically important diatom blooms have been replaced by widespread blooms of a large, green dinoflagellate, Noctiluca scintillans, which combines carbon fixation from its chlorophyll-containing endosymbiont with ingestion of prey. Here, we report that these massive outbreaks of N.