SOUTHEASTERN NORTH CAROLINA (AP) - If you have lived in the south most of your life, you've probably heard your parents or grandparents on a seemingly clear and hot summer night call silent, random flashes of light in the sky "heat lightning."
Some believe in the myth that "heat lightning" is caused purely by the sultry summer air; if you were told this by your family members, we are here to say that they were wrong.
But what is "heat lightning?" Is it real or an illusion and why doesn't it make a sound?
"Heat lightning" is real lightning from a thunderstorm that can be a significant distance, up to 100 miles, away from the observer. Many of the strikes that will be visible are intracloud.
What happens to the sound? Light travels much faster than sound, so this may be just because of the distance between you and the storm itself.
Another reason is due to the temperature and density of the air, especially at altitude. This will refract the sound of the thunder through troposphere that will in turn reflect off the earth's surface to create voids where thunder cannot be heard. The curvature of the earth's surface also plays a role in this too.
The general rule of the thumb still applies; when thunder roars, head indoors!