Winds and storms

Wind is the movement of air parallel to the Earth's surface. Winds are named according to the direction from which they are blowing. The direction of a wind is significant in weather forecasting.

In the Northern Hemisphere, for example, northwest winds usually indicate colder, drier weather. Easterly winds mean cloudiness and precipitation, and southerly winds mean warm, humid weather.

STORMS
A storm is a disturbed state of the atmosphere. It is marked by strong winds, rain, sleet, hail, and lightning. Thunderstorms, windstorms, and cyclones are different types of storms.

Thunderstorms
When hot, moist air is carried to great heights by the strong updraft in a rain-bearing cloud, the water vapor condenses. Then heavy rain, thunder, and lightning occur along with strong wind, and sometimes hail. This is a thunderstorm.

Windstorms
Meteorologists and mariners consider winds to be at storm strength when they reach a speed of 73 miles (117 kilometers) per hour. Windstorms, or gales, have little or no precipitation.

Sandstorms
Sandstorms and dust storms are dry windstorms. Sandstorms are associated with desert areas. They occur when high winds lift particles of sand into the air and drive them with great force.

Cyclones, hurricanes, and tornadoes
The word cyclone or hurricane is frequently used for any wind with a speed more than 75 miles (121 kilometers) per hour.

Cyclones often cover thousands of square miles. The swift winds often bring heavy rain.

A cyclone is a storm or system of winds that blows toward an area of low air pressure, over which they rotate in an inward spiral.

A tornado is a violent, inland cyclonic storm. The tornado has a funnel-shaped trunk that reaches down from a dark thundercloud and whirls at speeds up to 300 miles (482 kilometers) per hour.

Tornadoes can tear the roofs from houses.