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.

See also Clouds and cloud types; Weather forecasting

thun·der / ˈ[unvoicedth]əndər/ • n. a loud rumbling or crashing noise heard after a lightning flash due to the expansion of rapidly heated air. ∎  a resounding loud deep noise: you can hear the thunder of the falls in the distance. ∎  used in similes and comparisons to refer to an angry facial expression or tone of voice: “I am Brother Joachim,” he announced in a voice like thunder.• v. [intr.] (it thunders, it is thundering, etc.) thunder sounds: it began to thunder. ∎  make a loud, deep resounding noise: the motorcycle thundered into life the train thundered through the night. ∎  [tr.] strike powerfully: McGwire thundered that one out of the stadium. ∎  speak loudly and forcefully or angrily, esp. to denounce or criticize: he thundered against the evils of the age| [with direct speech] “Sit down!” thundered Morse with immense authority. PHRASES: steal someone's thundersee steal.DERIVATIVES: thun·der·er n.thun·der·y / -d(ə)rē/ adj.

thunder traditionally regarded as the destructive agent producing the effects usually attributed to lightning. In biblical phrases, thunder denotes great force and energy, as in Job 39:19.
steal someone's thunder win praise for oneself by pre-empting someone else's attempt to impress. The phrase comes from an exclamation from the English dramatist John Dennis (1657–1734), on hearing his new thunder effects used at a performance of Macbeth, following the withdrawal of one of his own plays after only a short run.

See also blood-and-thunder, sons of thunder, the Thunderer, Thundering Legion.

394. Thunder

See also 27. ATMOSPHERE ; 87. CLOUDS ; 246. LIGHTNING ; 345. RAIN ; 417. WEATHER .

brontograph

1. an instrument for recording thunderstorms.

2. the record thus produced. Also called brontometer .

brontology

Rare. a treatise on thunder.

brontometer

brontograph.

brontophobia

an abnormal fear of thunder and thunderstorms. Also tonitrophobia.

ceraunomancy

keraunomancy.

fulmination

thundering; the sound of thunder.

keraunomancy, ceraunomancy

a form of divination involving the interpretation of an omen communicated by thunder.

keraunoscopia, keraunoscopy

a form of divination involving the observation of thunder.

tonitrophobia

brontophobia.

642. Thunder (See also Lightning.)

1. Bromius epithet of Dionysus, meaning ‘thunder.’ [Gk. Myth.: Zimmerman, 43]
2. Brontes cruel Cyclops who controls the weather; able to cause great thunder. [Gk. Myth.: Parrinder, 47; Jobes, 241, 400]
3. Donar god of thunder; corresponds to Thor. [Ger. Myth.: Leach, 321]
4. Indra thunder god and controller of weather. [Vedic Myth.: Leach, 521]
5. Mjolnir Thor’s hammer. [Norse Myth.: Brewer Dictionary, 1076]
6. Thor god of thunder. [Norse Myth.: Leach, 1109]