The United States recently witnessed a power-packed storm system known as Derecho, making headlines due to its extraordinary attributes. One of the most peculiar things observed was the turning of the sky green during the storm. Derechos, although primarily observed in the US, have also been documented in countries like Russia, Germany, Finland, Bulgaria, and Poland. This article delves deeper into the world of Derechos, their types, and why they transform the sky into an unusual green hue.
Understanding Derechos
Derecho is a Spanish word translating to ‘straight,’ which perfectly describes this type of storm. A Derecho is a “widespread, long-lived, straight-line windstorm,” typically associated with a band of rapidly moving showers or thunderstorms. Unlike a tornado where the winds rotate, a derecho features straight-line storms.
These storms are capable of traveling hundreds of miles, covering a vast area in their wake. They are generally warm-weather phenomena occurring mostly in June and July. Although not as common as other storm systems like tornadoes or hurricanes, Derechos have had some significant occurrences. The Super Derecho of 2009, sweeping from Kansas to Kentucky, is considered one of the most intense and unusual Derechos ever observed in the US, boasting wind speeds of up to 170 km/hr.
Classification of Derechos
Derechos are categorized into three types based on their characteristics and occurrence- Progressive, Serial, and Hybrid.
A progressive derecho is linked with a short line of thunderstorms traveling across hundreds of miles along a rather narrow path, predominantly seen during summer.
The serial derecho, contrastingly, has an extensive squall line, wide and long, traversing a larger area. Serial derechos usually make their presence felt in the spring or fall season.
Hybrid derechos, as the term suggests, combine the features of both the progressive and serial derechos, making them a blend of these two types.
The Phenomenon of The Green Sky
A peculiar characteristic of Derechos, transforming the sky into a shade of green, is due to light’s interaction with the storm’s massive water content. Severe thunderstorms possess significant amounts of water in the form of heavy raindrops and hail. These scatter away all wavelengths except for blue, which primarily penetrates below the storm cloud. The blue light then mixes with the red-yellow hue from the afternoon or evening sun, resulting in a green sky. This phenomenon adds an eerie yet fascinating aspect to the storm.
Derechos, despite being less common than other storm systems, present an intriguing study due to their unique attributes. Be it their straight-line winds or the captivating green sky, Derechos are truly a marvel of nature.