Monsoons are typically associated with torrential downpours during warmer summer months, however, their lesser known sibling, dry monsoons, occur during winter. These monsoons play an important role in reducing air pollution, however, with Earth’s climate changing, their reliability is becoming increasingly unreliable. The source of monsoons is the Sun, which heats different parts of Earth’s surface unevenly. This creates two pockets of air with different temperatures, resulting in a difference in air density. The warmer air rises, and the cooler ocean air rushes in to take its place, thus creating wind. Dry monsoons don’t have the same excitement as wet monsoons, but they have an important job - they carry away pollutants. Winter monsoons carry pollutants like carbon monoxide and lead in the air out to the ocean, and when it rains, the pollutants sink to the bottom. Wet monsoons also help to reduce pollution by gathering pollutants in the air and sending them into the ground. However, some pollutants extracted by winter winds aren’t carried to the ocean’s bottom - they are pushed up above the monsoon clouds into the stratosphere. We love the ozone layer because it blocks most of the Sun’s harmful ultraviolet light from reaching us. Unfortunately, pollutants in the atmosphere can react with ozone molecules and break them down, particularly around the poles. We were able to reverse this trend thanks to an international treaty in 1987 that banned the use of ozone-depleting chemicals. However, warming temperatures on Earth are causing monsoon seasons to change, which could affect our ability to carry atmospheric trash to places where it can do less harm.
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