Bow Echo:
The intense storms that hit Delhi recently looked like a crescent or an archer’s bow which in technical terms are called as “bow echoes.”
- A bow echo is essentially a line of storms, also called a squall line, on the radar that looks like a bow.
- This squall line can sometimes be embedded in a larger squall line.
- A bow echo can extend from 20 km to 100 km, and last between three and six hours.
- The term was coined in the 1970s by Ted Fujita, a Japanese American meteorologist known for developing the scale to classify tornadoes.
- When rain-cooled air comes down to the ground, and spreads out horizontally. As this happens, a boundary called the gust front is created between the rain-cooled air and warm-moist air on the surface.
- This front pushes up the warm-moist air into the atmosphere, which forms new thunderstorms.
- These new thunderstorms produce more rain, thereby creating more rain-cooled air, which helps the gust front to maintain its strength.
