DERECHO
Source: indianexpress
Context: The US states of Nebraska, Minnesota, and Illinois were hit by a storm system called a derecho. Winds gusting to 140km per hour snapped powerlines and knocked down trees
What is Derecho?
The US National weather service describes a derecho as a "widespread, long-lived, straight-line windstorm" that is associated with " rapidly moving showers or thunderstorms"
The name comes from the Spanish word "la Derecha" which means "straight".
Unlike a tornado or cycle winds in straight line storms have no rotational motion
- Being a weather phenomenon, a derecho occurs usually in summer times beginning in May, with most storms hitting in June and July
- These rarely occur when compared to tornados or hurricanes
- for a storm to be classified as a derecho, it must have a wind speed of 93 km per hour, and a wind damage swath extends more than 400km
- The successive wind damage gaps should not be more than 3 hours (according to the Oklahoma School of Meteorology)
Green Sky
Severe thunderstorms can result in a 'green sky' due to light interacting with the vast amount of water they hold.
Big air drops and hail can scatter all but the blue wavelengths, because of which primarily blue light penetrates below the storm cloud
This blue then combines with the red-yellow of the afternoon or evening sun to produce green
American Storm
Derecho occurs mostly in Central and eastern United States, the super derecho of May 8, 2009, was one of the most intense and unusual Derechos ever observed
- A progressive derecho is associated with a short line of thunderstorms that may travel for hundreds of miles along a relatively narrow path (it is a summer phenomenon)
- A serial derecho has an extensive squall line- wide and long - sweeping across large areas (during spring or fall )
- Hybrid ones have both features of serial and progressive derechos
