Thunder

Thunder is the noise caused by lightning in a thunderstorm, when the release of heat energy results in audible shock waves in the air.

A thunderstorm is a storm that produces lightning and thunder, and occurs in cumulonimbus clouds . Cumulonimbus clouds are large, tall clouds with very strong updrafts that transport water high into the atmosphere. Thunderstorms can also produce flash floods , hail, strong winds, and even tornadoes. At any time on Earth, about 2,000 thunderstorms are taking place, from mild rainstorms to very damaging hailstorms with high winds. In general, the higher the storm clouds, the more violent the resulting storm will follow. Under certain conditions, isolated thunderstorms can even merge to form large convective complexes with increasing power and damage capabilities. Thunderstorms and lightning can cause not only billions of dollars of damage every year, but also result in loss of human and animal life, since about 100 people die per year in the United States from causes associated with lightning.

Lightning is a large electrical discharge produced by thunderstorms as a huge spark, which can heat the air as much as several times hotter than the temperature of the surface of the Sun (about 54,000°F or 30,000°C). This heated air causes expansion in the air when the electrical charge of lightning passes through it, and forces the air molecules to expand. As they expand, the air molecules require more space and they bump into cooler air, creating an airwave, the sound of thunder. It travels in all directions from the lightening at the speed of the sound (330 m/s); therefore, it takes the thunder about five seconds to travel each mile, or about three seconds to travel one kilometer. Because light travels faster than sound, the lightning is always seen first, before the thunder is heard. Measuring the time between the lightning and the thunder can give an approximate estimate of how far the observer is from the thunderstorm.

Depending on the location of the observer or the type of lightning, thunder can produce many different sounds. When lightning strikes nearby, the resulting thunder is usually interpreted as a short and loud bang, whereas thunder is interpreted as a long, low rumble when it is heard from far away. Thunder can also sound like a large crack, or a clap of thunder followed by rumbling, or a thunder roll. Lightning always produces thunder, and without lightning, there is no thunder in a thunderstorm. Sometimes, when the lightning is too far away for the sound waves to reach the observer, lightning can be seen but no thunder can be heard. This is known commonly as heat lightning, and it happens because the dissipating sound of thunder rarely travels farther than ten miles, especially in lowlands or at sea.

Edited by, Nirrosa Muniandy