These are winds that change direction according to the seasons, carrying moist air from the ocean to the continent in one season and dry air from the land to the sea in another. The phenomenon occurs in approximately 25% of the planet’s tropical area, but its effects are more visible in South and Southeast Asia, especially in countries such as India, Pakistan and Bangladesh. Over there, the winds bring torrential rains from June to August, the Indian summer period, but leave the region starving in winter, between December and February. In India, the importance of the monsoons is so great that the climate governs many of the country’s habits, as meteorologist Carlos Augusto Morales, from the University of São Paulo (USP) remembers: “When the rains don’t come at the right time, the main economic activity in the region, the planting of rice is seriously impaired.
Furthermore, it is in the months of major storms that the baby-bearing rate explodes. As the rains can last for several days, the population hardly leaves their homes. So…». On the other hand, the dry months are also quite severe for the locals. In the last two weeks of May this year alone, for example, thermometers spiked to 48.6ºC, killing 489 people. The situation gets much worse when the waters are delayed – or simply do not come. In one of the most serious droughts on record, which occurred in 1770, the monsoon rains failed and killed about 10 million people in the region of Bengal, in eastern India.
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seasonal shower The winds on the Indian continent determine the wet and dry seasons.
1 – In summer, the mainland heats up quickly, reaching 45ºC. The ocean heats up much more slowly, keeping the temperature close to 20°C. The terrestrial heat warms the air in the region, which rises to the upper layers of the atmosphere. The free space is occupied by strong winds that come from the Indian Ocean
2 – Ocean gusts bring a lot of moisture from the sea, creating rainstorms over the continent. The rising air carries vapor from the atmosphere, generating huge clouds. It is the “wet phase” of monsoon weather. During this period, which runs from June to August, torrential rain lasts up to a week.
3 – In winter, the continent is already much colder than the ocean, causing the air flow to change direction. Now, it’s the cold, dry wind from the Himalayan range that blows out to sea. As there is not enough moisture to form clouds over the continent, the “dry phase” of the monsoons in South Asia begins.
4 – The same cold breath that blocks the rains in India will mess with the climate of the north of Australia and the northeast of Indonesia. It is in these regions that the cold air meets the warmer air above the Indian Ocean, causing heavy rains from December to February, the summer time in the southern hemisphere.