Weather of Arabia - Thunderstorms are known as a climatic disturbance that occurs during a short period of time, and are always associated with lightning, thunder, heavy clouds, strong winds, heavy rain or hail.
Thunderstorms occur in almost any region of the world, but they are rare in the polar regions and at latitudes higher than 50 degrees north and 50 degrees south, and therefore the temperate and tropical regions of the world are most vulnerable to thunderstorms.
Thunderstorms arise when currents of warm and moist air ascend in a rapid upward movement to cooler regions of the atmosphere, and the moisture (water vapor) in the rising air condenses, causing instability and towering cumulonimbus clouds ( Towering Cumulonimbus Clouds ) are formed, and then occurs Precipitation, in addition to the process of condensation releases latent thermal energy, which further fuels the movement of rising air and increases instability.
As for lightning and thunder, it occurs after the electric charges resulting from friction accumulate on the particles of water or ice carried by the clouds. Shock waves , which are heard in the form of thunder.
The movement of air rises in the atmosphere in several ways; A common mechanism is the heating of the Earth's surface and adjacent layers of air by sunlight. If the surface heating is sufficient, the temperatures of the lower layers of air will rise faster than those in the upper layers, and the air will become unstable. The Earth's ability to quickly absorb the sun's heat is Because most thunderstorms form over land rather than oceans, instability can also occur when layers of cold air are warmed from below after moving over a warm ocean surface or over layers of warm air.
Mountains can also lead to upward movement of air by acting as topographic barriers that force winds to rise. Mountains also act as high-level sources of heat and instability when their surfaces are heated by the sun.
Thunderstorms used to be classified according to where they occur, such as local, frontal, or orographic thunderstorms (caused by mountains), but it has become common to classify them according to their characteristics, and these characteristics depend to a large extent on the atmospheric environment in which the storms develop, and the following are the types of thunderstorms :
1. Single-cell thunderstorms
They are weak, short-lived storms that grow and die within an hour or so. Solar heating is an important factor in triggering single-cell thunderstorms. Most of these storms occur in the late afternoon and early evening, when surface temperatures are highest. levels, and single-cell storms may result in heavy rain.
2. Multi-cell thunderstorms
A multi-cell storm is a common and diverse thunderstorm in which new barriers form along the leading edge of rain-cooled air (the storm front). Individual cells usually last 30 to 60 minutes, while the whole system may last for several hours. Multi-cell storms may produce hail and wind Strong, short hurricanes and floods.
3. Squall line thunderstorms
It is called a squall line, which is a group of storms arranged in a line, often accompanied by "whirlwinds" of strong winds and heavy rain, squall lines usually pass quickly and are less likely to produce tornadoes, and can be hundreds of miles long but are usually 10 or 10 meters wide Only 20 miles.
4. Supercell Thunderstorms
It is a long-lived (more than one hour) and highly organized storm, feeding from an updraft in a rotating and oblique manner, with a diameter of up to 10 miles and an altitude of 50,000 feet. This mesocyclone can exist from 20 to 60 minutes before Storm formation, most large and violent storms and tornadoes come from giant cells.
A thunderstorm is classified as severe when the storm wind speed exceeds 94 km/h or if it produces large hailstones with a diameter of more than 2.5 cm.
Thunderstorms can be seen and detected with a variety of tools, the most important of which are satellite imagery and weather radar.
Satellites
Most areas of the Earth can be seen by weather satellites, as satellites from space take pictures of the Earth at regular intervals, to give information about the location of clouds. Meteorologists watch these images over time to observe rapidly growing clouds, which is evidence of the possibility of a thunderstorm, and satellites can also give information about the temperature of clouds, as clouds with cold tops are usually very high in the atmosphere, and this means That the cloud is long enough to be a thunderstorm, and after identifying the storm, meteorologists track the movement of these clouds to know the next areas that will be affected by the storm.
Radars
Weather radar (Doppler radar) is very important for meteorologists, because it enables them to detect rain and severe weather even when it is cloudy or dark, as Doppler radar sends electromagnetic waves that are reflected from water droplets in the atmosphere to the radar, and thus The reflected wave energy reveals how heavy the rain is and the presence of hail, Doppler radar can also show how the winds are blowing near and within the storm. This is useful in understanding the types of hazards that may accompany and result from a thunderstorm, and also helps the radar understand how a thunderstorm is feeding itself and how it is evolving.
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