Kevin Myatt

Latest entries from the Weather Journal blog

• Weather Journal remains on break
• Coastal low prompts Southwest Virginia flooding
• Hurricane Ida: Something extraordinary may be happening

About Kevin

Kevin Myatt grew up in Arkansas to the tune of tornado sirens and the rhythm of hailstones, aspiring to be a meteorologist before his studies and career were turned to journalism instead. Though he often chases storms, he prefers living in the cooler, more tranquil weather of the Blue Ridge. He moved to Roanoke in 1999 to take a job on the copy desk of The Roanoke Times; writing headlines and editing copy is his principal work for the newspaper today.

Each May, Kevin assists Pulaski County High School / Virginia Tech meteorology instructor Dave Carroll in leading college and high school students to the Plains to observe severe weather firsthand. The accounts of many of his storm chases can be found here on the storm chasing page of his weather blog on roanoke.com.

Kevin was an editor for "Hurricanes and the Middle Atlantic States," a book written by D.C.-area weather enthusiast Rick Schwartz and published by Blue Diamond Books that documents hurricanes striking the mid-Atlantic states since colonial times.

The Weather Journal column began in 2003 and appears on Friday's Virginia section front in The Roanoke Times. The Weather Journal blog began in 2006 and follows weather day-by-day between the larger columns.

Moisture affects how light dances through clouds

Reader question: What causes clouds to appear different shades of gray? What about the greenish color the sky/clouds can take on prior to a tornado?

Sunlight and the density of moisture are the two most important factors in cloud color.

The darkness of a cloud is determined by how much sunlight can get through it, which is largely determined by how dense the water droplets are within the cloud and how thick the cloud is.

The denser the cloud or the taller the cloud extends into the atmosphere, the more light it is likely to block, giving it a gray or even black appearance. Thinner clouds, with less dense moisture and/or less thickness, block less light, and so can appear white as more light penetrates.

Early- and late-day sunlight often adds a red or orange cast on clouds. I have seen deep blue, green and yellow shades in and around violent thunderstorms. Various theories have been advanced to explain the phenomenon, but the common idea is that it has to do with what wavelengths of light both reflected away by and refracted through the larger raindrops abundant in thunderstorm clouds that can tower up to 8 to 12 miles high.

If red light waves are reflected away, that leaves blue and green colors as the primary light waves getting through the clouds.

Keep in mind that whatever color you see in any cloud may appear differently to someone else viewing the same cloud from a different angle, as sunlight would reflect off it or refract through it differently.

Kevin Myatt's column runs Monday, Wednesday and Friday.