Weather and micro-climate blogs (Copyright WeatherCast)

C yclones are massive vortical (i.e. spinning) systems with immense kinetic and thermal energies, which form in the tropical oceans and move inland. They generally have a low pressure central core  surrounded by a high pressure anticyclone that helps in its intensification. Based on the core pressure & sustained peripheral winds, cyclones are categorised on a scale of 1-5. ( see: https://en.wikipedia.org/wiki/Tropical_cyclone_scales ) For any tropical cyclone, six key fluid dynamical parameters govern their genesis & track. (a) Sea surface temperature (>27 deg C for assisting cyclone genesis) (b) Effect of Coriolis force (f - parameter) (c) Low pressure centre (typically < 990 millibars) (d) Wind shear (<10 s  -1 ) (e) Presence of adjacent high pressure envelopes (which hinders with its movement) or any other phenomenon like a Western Disturbance and ITCZ movement. (f) Upper level steering winds. CYCLOGENESIS/INTENSIFICATI...

E lNino Southern Oscillation, abbreviated as ENSO, is an interesting and a well-established interseasonal phenomenon that has an immense effect on the tropical monsoons. Very briefly, it is associated with the weakening or full reversal of the atmospheric Walker circulation cell, which forms in the Pacific Ocean. The Walker cell's preferential direction is east-west (easterly), created by the motion of trade winds, supplying moisture to Australia & Indonesia. However, during an ElNino cycle, it either weakens (thereby slowing down the trade winds) or fully reverses, where the trade winds now blow west-east (westerlies).  The Walker cell formation and its modification is driven by the ocean dynamics. During non-ElNino or neutral years, a cold pool exists in east Pacific - near South American coast due to upwelling (specifically Chile coast), and a warm pool is formed in the west Pacific - near Australia. This set up is quashed by a Kelvin wave , which one can  ...