Thunderstorms, lightning and many such events are witnessed during Pre-monsoonal season in India. Explain their formation process and its impact on various regions of India.
Pre-monsoon season is from April to May in India. It is the precursor to the full onset of monsoon. Due to high-pressure over the Indian subcontinent, the moisture bearing winds are not attracted to the mainland.
Process of Pre-monsoon rainfalls:
- Oppressive heat is common in summer. It leads to warm air rising conventionally.
- This warm, light air ascends to considerable height in the atmosphere.
- Moreover the temperature of the air parcel reduces and its humidity capacity also falls.
- Thus clouds are formed due to condensation of water vapour in the air.
- The size of clouds increases due to accumulation of water droplets.
- When clouds become too heavy, torrential rain and lightning occur.
- Therefore cumulonimbus clouds formed by convectional heating of air, lead to rain.
In some regions, this rainfall has positive impact:
- Aids coffee cultivation in Kerala and Karnataka (Blossom showers).
- Helps the mango crop develop in Karnataka (Mango showers).
However, this has an adverse impact elsewhere, in form of natural disasters/discomfort:
- Kal Baisakh – Rains in West Bengal.
- Bardoli Chheerha – Heavy rain and rain in Assam.
Therefore the pre-monsoon and thunder storms originate due to unique reasons. They have proven a mixed blessing for India.