Sun Directly Over Java, IPB Professor Explains Why Jakarta Is Hotter While Bogor Is Still Experiencing Rain
In October, the sun’s position directly over Java increases the intensity of solar radiation reaching the Earth’s surface. However, the impact on the weather varies by location: Jakarta tends to be hotter, while Bogor is still likely to experience rain.
This was explained by Sonni Setiawan, SSi, MSi, a lecturer in the Department of Geophysics and Meteorology at IPB University. He noted that the sun’s position during this period is one of the factors that can influence the rise in surface temperatures on Java.
“Short wave radiation from the sun received by the surface can increase surface temperatures, especially when cloud cover is insufficient to block that radiation,” said Sonni.
Why Is Jakarta Hotter?
The temperature rise is felt most acutely in urban areas like Jakarta, which are dominated by buildings and paved roads. Sonni explained that these changes in land cover affect the surface’s ability to absorb and store heat.
“As the surface’s heat capacity decreases, warming from solar radiation can lead to a greater increase in surface temperature. As a result, the long wave radiation re emitted by the surface also increases,” he explained.
The presence of water vapor and air pollution also contributes to the absorption of long wave radiation energy from the Earth’s surface into the atmosphere.
“The more energy absorbed by certain gases and particles, the more long-wave radiation from the Earth is absorbed, trapping that energy before it is re emitted. This process is linked to the greenhouse effect, which can raise air temperatures in urban areas,” he elaborated.
Why Is It Still Raining in Bogor?
Meanwhile, regions that receive the same amount of solar heating can experience different weather conditions. This year’s El Nino phenomenon has also influenced cloud formation and rainfall distribution on a large scale. During El Nino, clouds that typically form in the Maritime region generally shift toward Peru. However, cloud formation and rainfall can still occur, albeit on a local scale.
In Bogor, geographical conditions play a role in the formation of local rainfall. The interaction between air movement and topography, particularly in the southern, eastern, and western parts of the Bogor region, can drive cloud growth, leading to rainfall.
“Throughout October, the interaction between moist air movement and topography in the Bogor region can trigger cloud growth and rainfall. The resulting rainfall is localized, so it does not always occur evenly across the entire Bogor region,” he explained.
Close by, Yet Different
Thus, temperatures and rainfall in the Greater Jakarta area are influenced by various factors, ranging from the sun’s position, land cover characteristics, atmospheric conditions, to topography. Consequently, hot weather and local rain can occur in close succession in relatively nearby areas. (AS) (IAAS/WSG)
