‘Local winds getting stronger’

How is global warming disrupting the wind systems?

If the atmosphere is the first blanket on Earth then, the emissions of greenhouse gases and the warming it is causing is creating a second blanket on top. This second layer is mostly water vapour, which is also a greenhouse gas. Warmer atmosphere holds more moisture, which results in a cycle we now find ourselves in. This has increased the average global temperature by 1.2˚C in the past 180 years or so.

Winds flow because of the force generated by the pressure differences. If the pressure gradient is higher then the winds will be stronger, and vice versa. With excess warming, the larger pressure gradient between the polar regions and the equator has decreased, which slows down winds, but locally winds can become stronger.

The Intertropical Convergence Zone winds have become stronger locally, which has repercussions in terms of extreme weather events. This has been seen particularly in India, as the overall monsoon rainfall is not changing much but the number of heavy rainfall events is increasing. In the core monsoon region, which is mostly the central part of the country, it has been observed that light and moderate rains are decreasing while the heavy rains are increasing. Tropical cyclone numbers may not be increasing but their intensity is rising due to the winds inside them getting stronger mainly from the excess moisture.

How can we better measure winds to understand them and get to know how they are changing with the changing climate?

Winds are measured using ground-, air- and space-based instruments such as anemometers, radiosondes, doppler weather radars and satellites, but all of them have not been able to generate accurate profiles of winds as yet. This is especially true for tropical regions and oceans. Measurement of winds in these regions is especially difficult because the variations of temperature and pressure are slow. If we increase the network of our observation instruments on ground, we may be able to create accurate profiles of winds and changes.  

This was first published in the 1-15 July, 2024 print edition of Down To Earth