NEWS – The India Meteorological Department (IMD) has issued a warning of “above-normal” heatwave conditions across most parts of the country in April and May

HIGHLIGHTS

• Heatwave Conditions: The IMD forecasts above-normal heatwave conditions in various states including Gujarat, Maharashtra, Andhra Pradesh, north Karnataka, Odisha, and western Madhya Pradesh. These regions are expected to experience an increase in the number of heatwave days compared to the usual one to three days during April and May.
• El Nino Effect: The expected hotter-than-usual summers are attributed in part to the continuing effect of El Nino. El Nino, associated with heating of the Central Pacific surface waters, is linked to reduced rainfall in India, contributing to hotter and drier conditions.

HEATWAVES

• Heatwaves are prolonged periods of excessively hot weather with adverse impacts on human health, the environment, and the economy.
• India, being tropical, is vulnerable to more frequent and intense heatwaves.

IMD Criteria for Declaring Heat Wave:

• Threshold temperatures for Plains (40°C) and Hilly regions (30°C).
• Increases from normal temperature define heat wave (5-6°C for ≤40°C, 4-5°C for >40°C).
• Severe heat wave conditions (7°C or more above normal, or 6°C for >40°C).
• Heat wave declaration if actual max temperature is 45°C or more.

Causes of Heat Waves:

• Global Warming: Human activities increasing Earth’s average temperature.
• Urbanisation: Urban heat island effect due to high-density cities.
• Sparse Pre-Monsoon Showers: Less moisture leading to dry conditions.
• El Nino Effect: Increased temperatures in Asia affecting weather patterns.

Impacts of Heat Waves:

• Health: Heat-related illnesses like heatstroke and hyperthermia.
• Water Resources: Exacerbating water scarcity and competition for resources.
• Energy: Strain on power grids due to increased cooling demand, impacting productivity and vulnerable populations.