THUNDERSTORMS

THUNDERSTORMS

Subject: Geography

Context: The Regional Meteorological Centre, Chennai, has said that rainfall occurred at isolated places over Kerala and Mahe during the 24 hours ending on Monday morning.

Outlook for Monday had hinted at the possibility of thunderstorms with lightning at isolated places over Tamil Nadu and Kerala.

Concept:

• Thunderstorms and tornadoes are severe local storms. They are of short duration, occurring over a small area but are violent.
• Thunderstorm is a storm with thunder and lightning and typically also heavy rain or hail.
• Thunderstorms mostly occur on ground where the temperature is high. Thunderstorms are less frequent on water bodies due to low temperature.
• Worldwide, there are an estimated 16 million thunderstorms each year, and at any given moment, there are roughly 2,000 thunderstorms in progress.

Motion of a thunderstorm

• Path of a thunderstorm is erratic. Motion is primarily due to interactions of its updrafts and downdrafts.
• The speed of isolated storms is typically about 20 km (12 miles) per hour, but some storms move much faster.
• In extreme circumstances, a supercell storm may move 65 to 80 km (about 40 to 50 miles) per hour.

Downbursts

• Downdrafts are referred to as macrobursts or microbursts.
• Macroburst is more than 4 km in diameter and can produce winds as high as 60 metres per second, or 215 km per hour.
• A microburst is smaller in dimension but produces winds as high as 75 metres per second, or 270 km per hour
• They are seriously hazardous to aircrafts, especially during takeoffs and landings.