The Nights Feel Colder? BMKG Explains The Cause

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JAKARTA - The Meteorology, Climatology and Geophysics Agency (BMKG) explained that the phenomenon of colder night air temperature in several areas on the island of Java was caused by the movement of cold and dry air from Australia.

BMKG stated that cold air temperature is a natural phenomenon that commonly occurs in the peak months of the dry season, namely in July-September.

Currently, the area of Java to East Nusa Tenggara (NTT) is heading for the peak period of the dry season. This period is marked by the movement of winds from the east, originating from the Australian continent.

BMKG Deputy for Climatology Herizal said that in July 2021 Australia will be in a winter period where air masses become cold and dry.

The pattern of relatively high air pressure in Australia causes the movement of air masses from Australia to Indonesia or known as the Australian Cold Monsoon.

"The Australian monsoon winds blowing towards Indonesian territory through the waters of the Indian Ocean which has a relatively colder sea surface temperature, causing temperatures in several regions in Indonesia, especially the southern part of the equator (Java, Bali, and Nusa Tenggara) to feel colder as well," Herizal said as quoted by Antara, Wednesday, July 7.

In addition to the impact of wind from Australia, reduced clouds and rain in Java to Nusa Tenggara also affect the cold temperature at night because the absence of water vapor and water causes the radiation energy released by the earth at night is not stored in the atmosphere.

Then the sky that tends to be clear of clouds will cause long waves of solar radiation to be released into the outer atmosphere.

"So then it makes the air near the surface feel colder, especially at night until the morning. This then makes the air feel colder, especially at night," he added.

Some people also attribute the cold air phenomenon to the "aphelion" or the position of the sun which is at its furthest point from the earth. Aphelion is an astronomical phenomenon that occurs once a year in the month of July.

BMKG confirmed that the sun is currently at the aphelion point but this condition does not have much effect on surface atmospheric phenomena.

"Meanwhile, at the same time, in general, Indonesian territory is in the dry season period. This makes it seem as if aphelion has an extreme impact on decreasing temperatures in Indonesia," he said.

The impact of the extreme temperature drop, said Herizal, could also cause several places such as Dieng and other highlands to experience the phenomenon of ice dew or upas dew resembling snow.

Meanwhile, BMKG Deputy for Meteorology Guswanto said that based on BMKG observations, currently the average minimum and maximum temperatures in the southern part of the equator, such as Java, Bali, and Nusa Tenggara, are generally lower than other areas in the north or around the equator.

"The minimum air temperature ranges from 14-21 degrees Celsius with the lowest temperatures recorded in Maumere, NTT, and Tretes, Pasuruan Regency, East Java," he said.