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❤️ Support the channel - https://donationer.blogspot.com/ ❤️ Thunder (older name: thunder) are electrical discharges in the Earth's atmosphere that manifest themselves in a flash of light (lightning) and a sharp or rumbling sound (thunderclap, thunderclap, thunderclap). These electrical discharges generate a lot of heat for fractions of a second, which causes the air to move, which is the source of the thunder. Thunder occurs in connection with cumulonimbus clouds (storm clouds), but can also occur in extremely rare cases in cumulus clouds (ordinary cumulus clouds) and stratus clouds (fog clouds). The discharge in cumulus clouds is usually much larger than in ordinary cumulus clouds, while the current strength in the lightning from fog clouds is usually lower than in lightning from cumulus clouds. There are indications that thunderstorms can occur in rare cases during sandstorms, volcanic eruptions and possibly avalanches. Air mass thunderstorms occur through local heating due to solar radiation, when warm and moist air is forced upwards. It can occur in both cold and warm air masses. Heat thunderstorms occur in warm and moist air masses, which means that it remains warm after the thunderstorm. Heat thunderstorms are often local. Frontal thunderstorms, also known as frontal thunderstorms, occur in connection with a cold front passing and being followed by significantly colder air. Frontal thunderstorms can be very persistent. The discharges are due to strong electrical charging of the different parts of the cloud. The physical background is not completely clear, but scientists know that there are several different mechanisms that lead to the electrical charging of clouds. One of these is based on the existence of cosmic radiation in the cloud and another such mechanism on piezoelectricity. Strong vertical winds with warm, moist air, supercooled water droplets and ice crystals, and an unstable atmosphere are common. One theory is that light, positively charged ice particles rise with the updrafts, while heavier, negatively charged ice/water droplets (so-called Graupel particles) and grain snow particles sink downwards due to gravity. When the grain snow particles come into contact with water droplets in the lower parts of the cloud, negative charge is transferred. Through direct measurements, it has been established that the upper parts of the cloud usually become positively charged and the lower parts negatively charged. Since cumulonimbus clouds have a large vertical extension, the potential difference can gradually become very large. When the insulating capacity of the air is exceeded, a discharge is triggered, usually between different parts of the cloud or between two nearby clouds, but sometimes also between clouds and the Earth's surface - lightning "strikes". A pre-discharge ionizes the air in bursts of about 50 meters until it reaches about 100 meters above the ground. Then the attraction of conductive objects from the ground is felt and a captive discharge is created that is drawn upwards. This meets the pre-discharge. The channel is now conductive and the main discharge from the ground to the cloud occurs at a speed of about one hundred million meters per second (one third of the speed of light). Normally, several discharges occur within a few tenths of a second. Some of these discharges can sometimes consist of a lightning bolt. The process is so fast that the eye does not have time to distinguish the different moments. A lightning channel, which can be 5–10 km long, is formed. The accompanying sound occurs when the heating (about 30,000 °C) of the air along the discharge path causes strong pressure changes. No point on the ground is reached by the sound from the entire lightning channel at the same time. It takes about 20 seconds for the sound to propagate along a seven-kilometer-long lightning channel. Anyone who is really close to a lightning bolt hears an intense but relatively short-lived sound and perhaps also the hissing sound from the lightning discharge. A cloud is electrically charged long before it reaches the stage of a cumulonimbus cloud and the cloud's net charge can be removed by rain. Very intense thunderstorms are usually generated by a variant of cumulonimbus clouds called a supercell. They are extremely uncommon in Sweden. Thunderstorms occur partly in the same air mass, air mass thunderstorms, and partly at the boundary between two air masses, frontal thunderstorms. Both phenomena create strong updrafts. Small water droplets can exist in a supercooled form, down to -40 degrees, but temperatures of down to -20 degrees are required before they begin to freeze to a greater extent. In a thundercloud, both unfrozen water droplets and snowflakes are required for lightning to be triggered. A thunderstorm sometimes extends all the way to the tropopause, where it ends in a classic anvil. Most thunderstorms in Sweden occur during the summer, when water vapor in the atmosphere is good.