I and my family have seen colored lightning, and it was quite spectacular. What is the explanation? What causes it?
—James Maso and family, East St. Louis, Ill.
Dear James and family,
There are at least three possible causes. First, lightning’s temperature can vary, affecting its color: blue when hot and red when somewhat cooler. Second, ionization, the breakdown of atmospheric gases into ions, is a likely cause. Ionization results from lightning’s tremendous heat. Ionized atmospheric oxygen and nitrogen emit blue light and ionized water vapor appears red due to the presence of hydrogen. Finally, certain colors may be blocked by dust, rain, hail, etc. as light moves from the lightning to our eyes. This scattering may lead to varied hues of the lightning.