What is a monsoon?

Definition and causes

A monsoon is a seasonal change in the direction of the prevailing wind. The term is most commonly used to describe the seasonal winds of the Indian Ocean, which blow from the southwest during the summer and from the northeast during the winter. Monsoons are caused by the differential heating of the land and ocean surfaces. During the summer, the land heats up more quickly than the ocean, which creates a low-pressure area over the land. This low-pressure area draws in winds from the ocean, which then bring moisture and rain to the land. During the winter, the land cools down more quickly than the ocean, which creates a high-pressure area over the land. This high-pressure area pushes the winds away from the land, which then causes the dry season.

Areas affected

Monsoons are not limited to the Indian Ocean. There are also monsoons in other parts of the world, such as the Pacific Ocean, the Atlantic Ocean, and the Gulf of Mexico. The Asian monsoon is the most prominent of the world's monsoon systems, which primarily affects India and its surrounding water bodies.

Impacts

Monsoons can have a significant impact on a region's climate, agriculture, and economy. The rainy season, which occurs from September to February, is a major source of energy for the Hadley circulation during boreal winter and brings much-needed rain to crops and water supplies. However, monsoons can also cause flooding, landslides, and other natural disasters. For example, the 2013 Uttarakhand floods in India were caused by heavy monsoon rains. The floods killed over 5,000 people and caused widespread damage to infrastructure and property.

Prediction and forecasting

Predicting and forecasting monsoons is a complex task. Scientists use a variety of methods to track and predict monsoons, including satellite imagery, weather balloons, and computer models. The India Meteorological Department (IMD) is responsible for forecasting the monsoon in India. The IMD issues a seasonal forecast for the monsoon each year, which provides information about the expected onset, duration, and intensity of the monsoon. Understanding monsoons is important in order to mitigate their impacts and maximize their benefits.

Additional resources

• India Meteorological Department
• National Weather Service: Monsoon Safety
• NASA: Global Precipitation Measurement