Dear Tom,

I have seen photographs of white and also of black tornadoes. What accounts for the difference?

—Ted Stonick, Riverton, Wisc.

Dear Ted,

The appearance of a tornado is an awesome spectacle and its color is certainly part of it. A variety of colors is possible, but a tornado’s color is not a reliable indicator of its strength. A tornado is made visible by condensation of water vapor in the funnel and also by dust and debris carried aloft by the storm’s wind. In the absence of these, a tornado will consist of clear air and will be invisible. This can happen when a tornado first forms or when the air is very dry. A tornado will appear dark when seen with the sun behind it and white or gray when sunlit. Dust carried aloft can give a tornado a red, black or orange color.