The Science Behind Your Staycation
“Rain, rain, go away, come again another day 🎵,” said pretty much no student, ever.
Just like last year, the start of classes has once again brought with it the start of the (very) rainy season and the torrential downpours that come with the class suspensions many of you so love. But just because there are no classes does not mean that there is no Lifenews, so let us dive, not into the swimming pool-converted streets, but into the science behind these storms.
If you have seen any news articles about the floods, you have likely encountered the word habagat. This is the local term for the Southwest Monsoon, which refers to the seasonal wind pattern that brings warm and moist air across the Philippines from the southwest. These winds are the reason for the rainy season, and usually stay from June until early October. But what do these winds have to do with the rain, and what is up with this specific time of year?
During the Northern Hemisphere’s summer, which occurs from around June 21 to September 22, the large landmass of mainland Asia heats up due to constant exposure to the sun’s rays. This causes hot air to rise over Asia, creating a low-pressure area over the land. Low-pressure areas form when warm air rises, leaving less air at the surface.
Meanwhile, the surrounding bodies of water remain cooler, as water requires significantly more energy to change its temperature than land. This then creates high-pressure areas over the waters.
Air naturally flows from areas of high pressure to areas of low pressure, so the moist winds from the oceans are pulled towards the Asian continent, passing through the Philippines along the way. As the warm, water vapor-saturated air hits the Philippine islands, it is forced upwards by the mountains and high terrain in a process called orographic lifting.
When the air eventually cools as it moves over the land, the water vapor condenses into thick clouds and precipitation, which is exactly what causes the long periods of rain. The habagat in itself already makes the country prone to heavy rains.
Then, of course, there is the matter of typhoons, of which the Philippines experiences around 20 per year. Weather we like it or not, our location makes us very prone to these tropical storms. Like the habagat, typhoons are not randomly generated—they involve a storm of factors brewing together to form.
First, there must be warm sea surface temperatures of 26.5°C or higher. Second, there must be quickly rising moist air to form thunderclouds. And finally, there must also be a Coriolis force, which is caused naturally by the Earth’s rotation and causes the necessary factors to spin together.
Given those factors, the Western Pacific Ocean, which lies just east of the Philippines and is one of the warmest ocean regions in the world, is the perfect breeding ground for typhoons.
Warm water heats the air above it, and when the now-lighter and warmer air rises, a low-pressure area is created beneath it. The concept of air moving from high-pressure areas to low-pressure areas is again demonstrated as air from surrounding areas (with higher pressure) rushes in to fill the low-pressure gap. This incoming air is also warm and humid, as it comes from the ocean surface, so it also heats, rises, and forms a new low-pressure area.
As this process repeats over and over again, the storm feeds itself until it creates the large, rotating systems of moist air that we know as typhoons.
Sometimes, these typhoons do not reach the land area of the Philippines. However, they can still affect us by strengthening the habagat. Typhoons are low-pressure systems that constantly draw in surrounding air. When they pass north or west of the Philippines, they suck in considerably more moist air from the southwest, essentially supercharging the monsoon.
Clearly, the Philippines is currently experiencing both the habagat and the coming of typhoons. Take the opportunity to enjoy the unexpected staycation, but do pray that the rains stop. Remember that although it may simply mean cancelled classes for us, millions of Filipinos are severely affected by the floods and heavy rains.
Anyway, stay dry, New Lifers! Hopefully, the only things flooding are your brains.
Sources:
https://scijinks.gov/solstice/
https://education.nationalgeographic.org/resource/hurricanes-cyclones-and-typhoons-explained/
https://www.pagasa.dost.gov.ph/climate/climate-advisories#
https://www.pagasa.dost.gov.ph/information/about-tropical-cyclone/
https://www.carbonbrief.org/guest-post-why-does-land-warm-up-faster-than-the-oceans/
