The appearance of Arcus clouds is like a tsunami. BMKG remembers arcus clouds, which are like tsunami waves, a sign that heavy rains often occur from September to February
Netgenz - Technology | The Meteorology, Climatology and Geophysics Agency (BMKG) of Banjarmasin Station explained that Arcus clouds or tsunami clouds generally occur during the changing season (transition) and the rainy season from September to February. The transition season, which often produces clouds that look like rolls of tsunami waves, occurs in September, October, and November. While the tsunami clouds occur in the rainy season in December, January, and February.
A tsunami cloud is a popular term used by residents to describe the event "arcus cloud" because it has a shape that resembles a roll of tsunami waves. This incident was seen in the Banjarbaru area, South Kalimantan at the end of last week (24/9) at 07.30 WITA.
"This event can cause rain and hurricanes...(But) this Arcus Cloud atmospheric event has NOTHING to do with terrestrial events such as Earthquakes, Tsunamis, and others," noted the Banjarmasin Meteorological Station via the official Instagram account of the South Kalimantan BMKG @cuacakalsel, Sunday (26/9).
Is that a tsunami cloud?
A tsunami cloud or Arcus cloud is a type of cumuliform cloud that has a low altitude above the surface. A member of the Disaster Analysis and Reaction Team (TREAK), Center for Atmospheric Science and Technology (PSTA) of the National Aeronautics and Space Agency (LAPAN), Ina Juaeni, explained that Arcus clouds are generally created at an altitude near the surface of up to 1.9 km.
The presence of these clouds can be accompanied by cumulonimbus storm clouds and they are both attached or separated. Arcus in the form of long rolls horizontally is generally separated from the parent cloud (Cumulonimbus), and flat or long planar Arcus clouds are horizontally combined with the base of the Cumulonimbus cloud. Initially, the Arcus cloud event was seen in Meulaboh, Aceh last year (12/8/2020).
How was the Arcus cloud created?
Arcus clouds are created due to atmospheric instability, where warm, moist air masses move cold air masses. Therefore, as far as the face-to-face area, Arcus clouds are created and it will look like a giant tsunami wave roll.
Rolling clouds are created by wind shear. The outer side of the cloud looks soft while the inner side of the cloud looks rough due to strong winds. The appearance of the Arcus cloud is a sign that there will be strong winds soon. Either Arcus is a scroll or Arcus is flat as a warning that there will be a rainstorm.
In addition, Ina explained that arcus clouds in the form of scrolls are rare, flat shapes are often found. These clouds are generally found along the coast, but can also occur in non-coastal areas. So when there is a long cloud at the base of Cumulonimbus, it is an arcus cloud which means heavy rain will arrive soon.