Why does it hail in the hot summer?

Kainantu

Nearly everyone welcomes the warm, sunny days of summer. But with summer come thunderstorms, bringing tornadoes, flash floods, and hail. Although tornadoes and flash floods are dramatic by-products of thunderstorms, hail can be far more devastating to property and crops. Hail is formed in huge cumulonimbus clouds, commonly known as thunderheads. When the ground is heated during the day by the sun, the air close to the ground is heated as well. Hot air, being less dense and therefore lighter than cold air, rises and cools. As it cools, its capacity for holding moisture decreases. When the rising, warm air has cooled so much that it cannot retain all of its moisture, water vapor condenses, forming puffy-looking clouds. The condensing moisture releases heat of its own into the surrounding air, causing the air to rise faster and give up even more moisture. http://www.ucar.edu/communications/factsheets/Hail.html Aug 03 02, 1:14 PM

Kainantu

Convective storms form when cold air masses meet relatively warm moist air masses and a strong convective current develops. As the warm moist air rises it begins to condense releasing energy. The latent heat of vaporization of water is about 540 calories/gram. This energy increases the force of the updraft and accelerates the development of the storm. The droplets continue to cool. As they move further upward these droplets become super cooled. That is the droplets cool below the freezing point but remain in liquid form. How is hail formed? In general hail is formed when super cooled water droplets crystallize onto a frozen raindrop that has become suspended high up in a cloud. There are several ways this can happen. Sometimes the frozen droplets travel up and down in the cloud growing into a layered hailstone. Other stones form while suspended in one place, while still others form around a raindrop that is carried high into the cloud and freezes. Eventually the mass of the hailstone increases to the point that the force of gravitational pull on it exceeds the force of the updraft and the stone falls to earth. Falling rain and hail create downdraft of cold air. Hailstones can vary in size from a pea to that of a large orange. On the eastern plains of Colorado 1/2 - 3/4 inch diameter hailstones are common. At one time it was believed that the hailstones fell directly downward, but subsequent research indicates that often hailstones travel not vertically but laterally in the cloud sometimes shooting out the side of the cloud and appearing to come out of a cloudless sky. Aug 03 02, 1:17 PM

_princess_007

Hail is most common in mid-latitudes during early summer where surface temperatures are warm enough to promote the instability associated with strong thunderstorms, but the upper atmosphere is still cool enough to support ice. http://en.wikipedia.org/wiki/Hail Nov 17 06, 4:09 AM