The Southwest Monsoon, also known as Habagat
While the monsoon is interesting, it could be hard to understand at first glance. It is primarily driven by the difference in temperature between land and sea. These temperature gradients cause high and low pressure areas in different parts of the globe. Winds then flow from high pressure areas to low.
Another interesting driver of the monsoon is topography. Notice how the wind flows from the Indian Ocean, and then boomerangs from Africa towards India? This is because the eastern region of Africa is home to the East African Highlands. With peaks reaching more than 4,000 meters above sea level [1], these mountain ranges don’t allow the warm, moist air to pass. This air then gets redirected towards India.
Interestingly, some of these winds don’t even reach Africa or India, but immediately get redirected towards Southeast Asia. This is our local southwest monsoon, or what we call Habagat.
Supposedly the monsoon is not scary at all. But it is understandable that some people are scared because the media has been in overdrive with regards to reporting as all these rains coming from the southwest monsoon. Flood and rains are happening left and right, and a lot of classes have been suspended the past weeks.
However we also have to understand that this same monsoon contributes as much as 43% of the rainfall we receive in the Philippines [2]. Without the monsoon, our river basins and dams will be empty.
So, whenever PAGASA and the news announce that thunderstorms and rain are coming because of the monsoon, don’t be too scared. Just don’t forget to bring your umbrellas and leave for work or school earlier than usual (assuming classes are not suspended).
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1. https://www.britannica.com/place/East-African-mountains
2. Asuncion, J.F., Jose, A.M., 1980. A study of the characteristics of the northeast and southwest monsoons in the Philippines. NRCP Assisted Project. 49pp. (available from the Philippine Atmospheric Geophysical and Astronomical Services Administration, Quezon City, Philippines)
