The Fujita scale, developed by Dr. T. Theodore Fujita at the University of Chicago, ranks tornadoes from F0 to F5, with F0 indicating a tornado that does light damage and has wind speeds up to 73 mph. An F5 tornado does incredible damage and has wind speeds greater than 261 mph. Only 2 percent of tornadoes reach the F5 level. They Say the Sky Turns Green Before a Tornado. Clouds often take on a greenish hue before severe storms, but this is most often associated with hail.
Hail is usually part of a tornado-bearing cloud.
The very tall, dense cloud is most likely not letting in any sunlight, so the greenish tint may be a reflection of Earth's green foliage, although the cause of the green tint has not been proved conclusively. Tornadoes do not hit mobile homes more frequently than they hit other structures. It's just that mobile homes are more vulnerable to tornado damage. Mobile homes can easily be overturned by strong wind gusts. In addition, their thin walls make them susceptible to windblown debris.