Severe Storms

Blizzard:: This is a storm when strong winds 80 kmh (50 mph) or more at ground level occur following a winter frontal storm. There is a directional change in the wind, with airborne snow and ice particles in blinding proportions. Snowdrifts are created by gusty winds.
Cloudburst:: This is a sudden burst of very heavy rain from a vigourous cumulonimbus cloud, occuring in summer. Flash floods may be created in mountain areas in dry beds.
Derecho:: This is a special form of downdraft. It is stronger than 93 kmp (58 mph) and at least 451 km (280 miles) long, traveling an average of 36 m (118 feet) per second. It forms a windy squall line of thunderstorms in very humid weather, with strong winds in the middle layers of the atmosphere. It is formed when cold, dry air from above meets warmer, humid air below.
Dust Storm:: This is created in dry barren regions by gusty winds. It can generate enough electricity to create lightning. It restricts visibility, and can reach the base of the stratosphere.
Firestorm:: This develops when a forest wildfire creates a cyclonic circulation. The highly unstable air pulls in surrounding air, making its own localized wind pattern and creating a greater fire. A blowup wildfire is intensified by a strong wind or a low jet stream.
Flooding:: This results from excessive precipitation or melting of ice and snow. A flashflood results from heavy rain over a watershed. It is also caused by a stalled large frontal storm, a hurricane moved inland, or a long-lasting moderated rainstorm. If severe, it can create slides or break dams.
Hail Storm:: This is formed rapidly in a severe cumulonimbus cloud. If the hailstones are caught in updrafts, they are enlarged before eventually falling. The average sizeof hailstone is that of a marble. In more severe storms, the size of golf balls or even baseballs is attained. Damage to structures, crops, animals often occurs. The seeding of a cloud makes fewer large hailstones.
Heat Burst:: This is a high-temperature downburst, with strong, gusty winds, a dramatic rise in temperature, disintegrating thunderstorm, and a fall in atmostpheric pressure and dew point. Hot, humid air feeds the thunderstorm during the day. As thesun sets, the storm dissipates. Upper rain falls to the lower, cooler and drier part of clouds. It evaporates, then cools and falls. The air warms dramatically and is compressed as it falls, slamming into the ground and spreading out as a hot, dry burst of wind.
Ice Storm:: This occurs in winter in middle altitudes. It develops when warm moist air meets a cold air mass and slides up over it, forming precipitation above in cirrus clouds. As it falls through the cold mass, it freezes on contact with objects and the ground.
Katabatic Wind:: It is caused by a downward movement of air over mountains on the lee side, warming and drying while it descends. It gathers speed, up to 45 m/sec. (100 mph), till flat lands are reached. It then picks up moisture rapidly. Examples include the following: chinook, foehn, mistral, Santa Ana, and Washoe zephyr.
Lake Effect Storm:: This is a snowstorm occurring in the lee of large bodies of water when cold air crosses 16 km (10 miles) or more over much warmer open water. Polar air following a very low-pressure storm over area picks up moisture, and forms large high cumulus clouds. This storm may last for several days, and may deposit 1.2 to 1.5 m (4-5 feet) of snow in blizzard conditions.
Monsoon:: Although occurring in several parts of the world, the best known one affects India and nearby countries. It is caused by the uneven heating of the land masses. During the winter monsoon, the air over Tibet becomes a strong high-pressure area. The winds blow south to the Indian Ocean, not dropping any moisture. During the summer monsson, the high-pressure is replaced by a low-pressure area. The winds reverse direction, carrying much moisture, which they drop abundantly on the land. The moisture is necessary for crops, but too much creates flooding and other severe damage. Too little also can be devastating.
Mountainado:: This is a spinning vortex created as air flows over uneven mountains, most frequently in summer and winter. It is similar to a tornado on formation, but on smaller scale. The winds inside average 75 kmh (47 mph) and can cause much damage.
Sandstorm:: This is a dust storm on a much greater scale, occurring in sandy deserts. The wind carries sand 15 m (50 feet) into the air. It shifts sand mounds and creates dunes, burying rocks and fields.
Thunderstorm:: This is formed in cumulonumbus cloud. A positive electrical charge forms in the upper portion, and negative charge near the base. The reason for splitting not completely known. The negative charge of earth is repelled by the negative charge on the cloud. A positive charge induced on the earth, moving to the top of objects. Lightning occurs when the air no longer can insulate. This causes a sudden negative flow to the earth, followed by a positive flow to cloud. Extreme heat is created. The explosive expansion and contraction of the air creates thunder Some types of lightning are as follows: streak, forked, ball, and heat.
Tornado:: It is formed in cumulonimbus clouds when a southern flow of warm, very moist air, is topped by a westerly flow of cool, dry air. The squall line where they meet sets off convective clouds. The storm usually moves to the northeast. A funnel dips to the ground, with a sharply lowered pressure area being created in the vortex.
Tropical Storm:: It is formed in colonies of cumulonimbus clouds in low latitudes over the oceans. The wind motion is counter clockwise in the northern hemisphere and clockwise in the southern hemisphere. The ring of intensive convective clouds surrounding a cloudless centre is called the eye. The storm can generate winds up to 160 kmh (100 mph). It also creates high tides and heavy rains. It is known as a hurricane (Atlantic Ocean) or a typhoon (Pacific and Indian Oceans).
Waterspout:: It forms from an active cumulonimbus cloud over water, developing a long funnel dipping to the water. It creates strong winds and a disturbance of the water surface.
Whiteout:: This is the state of a blizzard whereby visibility cut to a few meters. It is also also produced by liquid droplets or ice-crystal fog. Within it, a sense of gravity can diminish. A ground blizzard is a special form, whereby vertical thickness of restricted visibility 1.8 m (6 feet).