From Western Disturbances to El Niño: Brief guide to climate terms this summer, Pg9

Key Highlights:

• Western Disturbances caused unseasonal rains in northern India.
• El Niño is expected to weaken the monsoon and intensify heatwaves.

Detailed Insights:

• Western Disturbances are moisture-laden wind systems originating beyond Afghanistan and Iran, crucial for winter precipitation in northern India.
• El Niño Southern Oscillation (ENSO), characterized by fluctuating Pacific Ocean temperatures, can disrupt global atmospheric circulation and weaken the Indian monsoon.
• La Niña, the opposite of El Niño, cools the eastern Pacific, typically strengthening the Indian monsoon and potentially causing floods.
• The India Meteorological Department (IMD) declares a heat wave when temperatures reach 40°C in plains or 30°C in hilly areas, with specific departure criteria.
• Apparent temperature or "feels like" temperature accounts for humidity and wind, reflecting the actual physiological stress experienced by the human body.

Key Concepts Involved:

• Heat Wave: A period of abnormally high temperatures relative to normal weather.
• Wet Bulb Temperature: The lowest temperature achievable through evaporative cooling of a water-covered surface.