In recent times, the India Meteorological Department (IMD) has forecasted severe heatwave conditions in certain parts of India, along with heavy rainfall in others. High temperatures beyond 42°C have been detected in parts of coastal Andhra Pradesh, Odisha, and Maharashtra, indicating a clear onset of heatwave conditions. This situation has arisen because of the dry northwesterly winds prevailing over northwest and central India.
Understanding India Meteorological Department (IMD)
The IMD was established in 1875 as an agency of the Ministry of Earth Sciences of the Government of India. The principal duties of this department include conducting meteorological observations, weather forecasting, and seismology. Whether it’s predicting weather changes or monitoring seismic activities, the IMD plays a vital role in safeguarding the country against natural calamities.
A Closer Look at Heat Waves
Heatwaves are characterized by abnormally high temperatures that soar above the average maximum temperature during the summer season. In India, these conditions are mostly felt in the northwestern and south-central regions. As a periodic phenomenon, heatwaves usually strike between March and June, and sometimes extend until July. With climate change further complicating matters, higher peak temperatures and more intense heatwaves become increasingly common occurrences.
The Criteria for Declaring Heat Waves
The criteria for declaring a heatwave are based on both the actual and normal maximum temperatures of a location. For plains, if the temperature reaches at least 40°C, and for hilly regions, if it touches 30°C, the conditions may be termed as a heatwave. However, when the normal maximum temperature of a place is less than or equal to 40°C, a rise of 5°C to 6°C is needed to declare a heatwave. In situations where the normal maximum temperature exceeds 40°C, an increase of 4°C to 5°C is required. Moreover, if the actual temperature crosses 45°C irrespective of the normal maximum temperature, a heatwave can be declared.
Health Hazards Posed by Heat Waves
Heatwaves carry potential risks to human health. The immediate effects range from dehydration, heat cramps, heat exhaustion to more severe conditions like heat stroke. Symptoms typically include fatigue, weakness, dizziness, headache, nausea, vomiting, muscle cramps, and sweating. Extreme temperatures and associated atmospheric conditions can exert physiological stress on individuals, leading, in some cases, to fatal consequences.
The Influence of Climate Change on Heat Waves
While climate change does not directly cause extreme weather events, it influences their occurrence. As climate change intensifies, episodes of heat waves are becoming more frequent. Future scenarios suggest that adopting a lower emissions lifestyle can help reduce the intensity and frequency of these heatwaves.
