Cheat Sheet

Weather For Dummies

Who doesn’t talk about the weather? But, if you know the meanings of some key weather words, you can talk even more fluently. And clouds provide scope for imagination and help in predicting and anticipating weather changes.

Key Weather Words Defined

If you want to talk about the weather, it helps to know the lingo. The following list contains words both common and uncommon you need to know to discuss weather and weather conditions knowledgably:

Atmosphere: The envelope of gases that compose the air surrounding Earth. Low pressure system: An area of rising air usually marked by cloudiness, often referred to as a storm.
Chaos: A state of a system in which disturbances large and small grow and decay. (The atmosphere is chaotic, and so is unpredictable beyond a few days.) Ozone hole: A thinning of the protective ozone layer in the stratosphere, often observed over Antarctica since the late 1970s during the Southern Hemisphere’s spring.
Climate: The average, long-term weather of a place. Precipitation: Water vapor that condenses in the atmosphere, falling to the surface as rain, snow, or ice.
Coriolis Effect: The “bending” effect of the Earth’s rotation on the path of things in motion in the atmosphere and the ocean. The bending or deflection of its course is to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. Pressure: The weight of the air overhead, exerted in all directions on everything air touches. Horizontal differences in pressure cause winds. Vertical differences in air pressure influence cloud formation and storm development.
Dewpoint: The temperature to which air must be cooled in order for it to become saturated with water vapor. Relative humidity: The percentage of the air that is saturated with water vapor at the current temperature. A value that changes with temperature. Air that is saturated at 50 degrees — 100 percent relative humidity — falls to about 50 percent relative humidity when its temperature rises to 70 degrees.
El Niño: The tropical Pacific Ocean becomes warmer, and air pressure changes, reducing the strength of east to west winds. These changes can affect weather in many parts of the world. Solstice: The point reached on or about June 21 and December 21 when the seasonal track of sunlight over the Earth reaches its northernmost and southernmost progress.
Equinox: Latin for “equal nights.” The time in spring and autumn when the Sun shines directly over the Equator and hours of daylight and darkness are equal everywhere. Stratosphere: The layer of much thinner gases in the atmosphere above the troposphere, between 7 miles and 30 miles in height. It includes the ozone layer. It is called the stratosphere because the temperatures are usually stratified and uniform at this level.
Global warming: The idea that the continual buildup of greenhouse gases in the atmosphere is leading to warming of temperatures that could alter climate patterns and seriously disrupt societies. Troposphere: The lowest part of the atmosphere, where all of the weather takes place. Its height averages about 7 miles, ranging from about 5 miles at the poles to about 10 miles at the Equator.
High pressure system: An area where more air has been added overhead than in surrounding areas. That accounts for higher barometric pressure. Typically, the air enters at high altitudes, sinks, and exits at ground level. The sinking motion causes warming and drying, leaving the clear sky often found in high pressure areas. Wind chill: The additional cooling effect of wind blowing on bare skin.

Types of Cloud

Clouds play a large role in discussing, predicting, and watching the weather — not to mention providing scope for daydreams and flights of fancy. The following list describes the common cloud types that form in various layers of the atmosphere — their names and what they look like — as well as clouds that form vertically.

  • High layered (above 17,000 feet):

    • Cirrus: Delicate white strands of ice crystals, often forming “mares tails.”

    • Cirrostratus: A veil of white cloudiness often covering the entire sky, causing “halos” around the moon and Sun and frequently indicating an approaching storm.

    • Cirrocumulus: Small white patchy patterns like fish scales and often called “mackerel skies.”

  • Middle layered (6,000 to 17,000 feet):

    • *Altostratus: Drab gray clouds of water droplets that obscure the image of the sun or moon. They can produce rain and snow.

    • Altocumulus: A darker, larger pattern of patchiness that may produce a shower.

  • Low layered (below 6,000 feet):

    • Stratus: Wispy cloud of fog that hangs a few hundred feet above the ground, often bringing drizzle.

    • Stratocumulus: Dark gray clouds, often covering the entire sky, which usually do not rain. They form rounded wavelike bands that are broken by blue sky.

    • Nimbostratus: Low, dark, ragged rain clouds that often bring continuous rain or sleet or snow.

  • Vertical clouds:

    • Cumulus: Large, billowy “cotton balls” of clouds with dark bottoms and bright white tops that can reach 10,000 feet high. May produce brief showers.

    • Cumulonimbus: Towering thunderheads, dark on the bottom and white anvil-shaped tops that can extend to 50,000 feet. Often produces lightning and heavy precipitation, including hail, and occasionally tornadoes.

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