Weather classification characterizes pre-Monsoon period as the hot season. Unlike peninsular and northeast India, the hot season gets extended for almost entire month of June over northwest India. The season is characterized by wide spread dust haze and extremely high temperatures over North India. There are heat islands even over central and eastern parts of the country. Dust storms (Andhis) over western India and thundersqualls (Norwesters) over eastern India become a regular feature. These are triggered by the influx of warm moist air in association with the Western Disturbances. Land and sea breeze effect is more prominent over the coastal areas. With the increased influx of moist air, the frequency of thundershowers increases progressively in South India. A few tropical cyclones form in the Indian seas threatening coastline on either side.
According to Skymet Meteorology Division in India, the most dangerous aspect is that, the season gets infested with far too many aviation weather hazards. Quite a few of these are the invisible ones which are also capable of striking without any notice. Paucity of preparation time leaves the air operations vulnerable to mishaps. Some of these invisible hazards need to be catered for, without fail, particularly during take off and landing phase.
High Temperatures: Surface temperature is the single most important and decisive factor for the `all out weight` for the airplane to lift off. The parameter becomes rather significant for shorter runways during extreme temperatures, particularly over North India where dry conditions prevail. Miscalculations of density altitude, if any, may lead to unpleasant situations during take off phase.
Wind Shear: Drop in surface pressure due to excessive heating may lead to gusty winds resulting in wind shear. The phenomenon may also be experienced in case of dissipation of vertical clouds in the vicinity of aerodrome. Speed and direction of prevailing winds remain a critical factor, both, for take off and landing run.
Turbulence: High temperatures do give rise to eddies and thermals in the lower levels, particularly over an uneven terrain. Uncontrolled swaying and bumpiness may lead to anxious moments for the air travellers.
Wake Turbulence: Take off and landings are in quick succession at some of the busy airports like Delhi, Mumbai, Kolkata and Chennai. Heavy body aeroplanes have very powerful engines which do leave lot of turbulence in its wake on the approach and take off leg. This specially gets accentuated during the hot and dry atmospheric conditions of pre-Monsoon, more so over North India.
In the recent past, technology and training has taken a big leap in the field of aviation. Technology demonstration of flying machines, along with high level of expertise of aircrew has mitigated the risk involved in complex air operations during adverse weather conditions. However, vagaries of weather are not advised to be taken lightly at any stage of flying missions.
