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A cloudburst is an extreme amount of precipitation, sometimes accompanied by hail and thunder, that normally lasts no longer than a few minutes but is capable of creating flood conditions. A cloudburst can suddenly dump large amounts of water e.g. 25 mm of precipitation corresponds to 25000 metric tons/km2 (1 inch corresponds to 72,300 short tons over one square mile). However, cloudbursts are infrequent as they occur only via orographic lift or occasionally when a warm air parcel mixes with cooler air, resulting in sudden condensation. At times, a large amount of runoff from higher elevations is mistakenly conflated with a cloudburst. The term "cloudburst" arose from the notion that clouds were akin to water-balloons and could burst, resulting in rapid precipitation; though this idea has since been disproven, the term remains in use. ==Causes== Cloud burst is actually a situation when the inter-molecular forces between the H2O molecules get very high due to the rapid decrease in the temperature or excess of electrostatic induction in the clouds causing the lighting to remain inside the cloud only, which causes hyperactive energy inside the cloud. The water molecules get denser and denser and get condensed but do not leave the cloud due to excess of electroforces. As the water concentration get higher and higher and so the weight gets heavier the water no longer is able to maintain force with the clouds and so they fall and it precipitates. A cloudburst can suddenly dump 25000 tons over one km2 (72,300 short over one square mile). This is quite a wallop and luckily it does not happen very often. A real cloudburst is very rare. Sometimes we call a sharp shower in the mountains a cloudburst when it really is not. The runoff from the slopes creates such a deluge that is seems that a cloud has burst open like a paper bag. Of course, even in a real cloudburst, the cloud does not break open. It happens because the rain forming in the cloud has been unable to fall down in a steady shower. Sometimes this happens when the cloud is ready to rain and the ground below is scorching hot. Either of these events causes a strong updraft of warm air. Raindrops find it very hard to fall through a current of rising air. When they start down, up they are whisked again, If this goes on for any length of time, the cloud gets an overload of rain. The drops that should have fallen are returned back up and new drops are being: formed all the time. Finally something happens to change the situation. The weight of rain is able to break through or maybe the updraft suddenly stops for some reason. Then all the raindrops, new ones and old, come tumbling down at once. Truly it seems as if the rain clouds burst. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Cloudburst」の詳細全文を読む スポンサード リンク
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