how thunderstorm form?

how thunderstorm( with hail in the upper past of the sky) form?( use english please)

4 個解答

  • ?
    Lv 6
    1 十年前

    [edit] Life cycle



    An airflow diagram of the towering cumulus stage.

    A given cell of a thunderstorm goes through three stages: the cumulus stage, the mature stage, and the dissipation stage.

    In the cumulus stage of a thunderstorm cell, masses of moisture are pushed upwards. The trigger for this can be solar insolation heating the ground producing thermals, areas where two winds converge forcing air upwards, or where winds blow over areas of high ground. The moisture rapidly cools into liquid drops of water, which appears as cumulus clouds. As the water vapour condenses into liquid, latent heat is released which warms the air, causing it to become less dense than the surrounding dry air, and so the air will tend to rise in an updraft due to the process of convection (hence the term convective precipitation). This creates a low-pressure zone beneath the forming thunderstorm. In a typical thunderstorm, some 5×108 kg of water vapour are lifted and the amount of energy released when this condenses is about equal to the energy used by a city (US-2002) of 100,000 during a month.



    An airflow diagram of the mature stage.

    In the mature stage, the warmed air continues to rise until it reaches existing air which is itself warmer, and the air can rise no further. Often this 'cap' is the tropopause. The air is instead forced to spread out, giving the storm a characteristic anvil shape. The resulting cloud is called cumulonimbus incus. The water droplets coalesce into heavy droplets and freeze to become ice particles. As these fall they melt, to become rain. If the updraft is strong enough, the droplets are held aloft long enough to be so large that they do not melt completely as they fall and fall as hail. While updrafts are still present, the falling rain creates downdrafts as well. The presence of both updrafts and downdrafts during this stage can cause considerable internal turbulence in the storm system, which sometimes manifests as strong winds, severe lightning, and even tornadoes. If there is little wind shear, the storm will rapidly 'rain itself out', but if there is sufficient change in wind speed and/or direction the downdraft will be separated from the updraft, and the storm may become a supercell.



    An airflow diagram of the dissipation stage.

    Finally, in the dissipation stage, updraft conditions no longer exist, and the storm is characterized largely by weak downdrafts. Because most of the moisture has precipitated out, there is not sufficient moisture in the lower air to sustain the cycle and the thunderstorm dissipates.

  • 1 十年前

    Thunderstorms commonly occur in spring and summer months in Hong Kong. On average, thunderstorms are reported at the Hong Kong Observatory in 5 days per month during April to September.

    Most thunderstorms form in cumulonimbus cloud. A cumulonimbus cloud typically covers an area of a few kilometres in diameter with a vertical extent of ten kilometres or more, like a tower hanging in the sky. The typical life span of a cumulonimbus cloud is a couple of hours.

    In the vicinity of active weather systems such as low pressure troughs, cumulonimbus clouds may form one after another. Such thunderstorms are more widespread and persistent. Occasionally, cumulonimbus clouds merge to form severe thunderstorms called supercells.

    On a summer day that sets off with fine weather, insolation may trigger the growth of cumulonimbus clouds and the formation of thunderstorms. Such thunderstorms are often localized and short lived. The weather may even be sunny not far away from the storms. Sometimes, the cumulonimbus clouds will drift with the wind and affect other areas. The areas of formation of the clouds may also vary with time.

    Thunderstorms are characterized by flashes of lightning and claps of thunder. In an unstable and moist atmosphere, water droplets and ice pellets in the cloud will become electrically charged in convective motion.

    If you encounter a tornado, seek shelter in a sturdy building. Stay away from windows, crouch to the floor and protect your head with your arms or thick padding. In the outdoors, stay away from trees, cars and other things that can be blown up by the tornado.

  • 1 十年前

    A thunderstorm, also called an electrical storm, is a form of weather characterized by the presence of lightning and its attendant thunder produced from a cumulonimbus cloud.[1] Thunderstorms are usually accompanied by heavy rainfall and they can also be accompanied by strong winds, hail and tornadoes. In the winter months, snowfall can occasionally take place in a thunderstorm. Such is often termed thundersnow.

    Thunderstorms form when significant condensation—resulting in the production of a wide range of water droplets and ice crystals—occurs in an atmosphere that is unstable and supports deep, rapid upward motion. This often occurs in the presence of three conditions: sufficient moisture accumulated in the lower atmosphere, reflected by high dewpoint temperatures; a significant fall in air temperature with increasing height, known as a steep adiabatic lapse rate; and a force such as mechanical convergence along a cold front to focus the lift.[2]

    Thunderstorms have had a lasting and powerful influence on early civilizations. Romans thought them to be battles waged by Jupiter, who hurled lightning bolts forged by Vulcan. Thunderstorms were associated with the Thunderbirds, held by Native Americans to be a servant of the Great Spirit. [citation needed]

    According to Encyclopedia Britannica, if the quantity of water that is condensed in and subsequently precipitated from a cloud is known, then the total energy of a thunderstorm can be calculated. In an average thunderstorm, the energy released amounts to about 10,000,000 kilowatt-hours, which is equivalent to a 20-kiloton nuclear warhead. A large, severe thunderstorm might be 10 to 100 times more energetic.

    And the thunderstrom also have many different type e.g Single cell storms ,Multicell storms,Squall line or multicell line storms,Supercell storms.

  • 1 十年前

    The positive and negative little eletricity in the clouds crash together and form thunder.