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24 Cards in this Set
- Front
- Back
cirrus cloud |
Cirrus clouds form high in the troposphere. Because it is so cold they are made of ice crystals. They are thin and wispy. Cirrus clouds don’t usually produce precipitation, but they may be a sign that wet weather is coming. |
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cumulus cloud |
Cumulus clouds are white and puffy. Convection currents make them grow upward and they may grow very tall. When they produce rain, they are called cumulonimbus. |
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dew point |
The temperature at which water vapor condenses is called the dew point. If this temperature is below freezing, ice crystals of frost form instead of dew. |
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fog |
Clouds form when air in the atmosphere reaches the dew point. Clouds may form anywhere in the troposphere. Clouds that form on the ground are called fog |
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freezing rain |
Freezing rain falls as liquid water. It freezes on contact with cold surfaces near the ground. It may cover everything with a glaze of ice. If the ice is thick, its weight may break tree branches and pull down power lines |
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hail |
Hail is another type of frozen precipitation. Hail forms in thunderstorms when strong updrafts carry rain high into the troposphere. The rain freezes into balls of ice called hailstones. This may happen over and over again until the hailstones are as big as baseballs. Hail forms only in cumulonimbus clouds. |
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heat index |
The heat index is a measure of what the temperature feels like because of the humidity. |
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humidity |
Humidity is the amount of water vapor in the air. High humidity increases the chances of clouds and precipitation. |
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relative humidity |
Humidity usually refers to relative humidity. This is the percent of water vapor in the air relative to the total amount the air can hold. How much water vapor can the air hold? That depends on temperature. |
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sleet |
Sleet forms when snow melts as it falls through a layer of warm air and then refreezes. It turns into small, clear ice pellets as it passes through a cold layer near the ground. |
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stratus cloud |
Stratus clouds occur low in the troposphere. They form in layers that spread horizontally and may cover the entire sky like a thick blanket. Stratus clouds that produce precipitation are called nimbostratus. The prefix nimbo- means “rain.” |
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weather |
Weather occurs because of unequal heating of the atmosphere. The source of heat is the Sun.Weather refers to the conditions of the atmosphere at a given time and place. |
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air mass |
ir mass is a large body of air that has about the same conditions throughout |
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anticyclone |
anticyclone is a system of winds that rotates around a center of high pressure. Anticyclones bring fair, dry weather. |
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cold front |
cold front occurs when a cold air mass runs into a warm air mass |
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cyclone |
A cyclone is a system of winds that rotates around a center of low pressure. Cyclones bring cloudy, wet weather. |
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front |
The boundary between two air masses is called a front |
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occluded front |
occluded front, a warm air mass becomes trapped between two cold air masses. |
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stationary front |
Sometimes two air masses stop moving when they meet. These stalled air masses create a stationary front |
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warm front |
When a warm air mass runs into a cold air mass it creates a warm front |
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blizzard |
A blizzard is a snow storm that has high winds |
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hurricane |
hurricane is an enormous storm with high winds and heavy rains. |
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lake-effect snow |
If they are near a lake, they may be getting lake-effect snow |
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lightning |
Lightning is a huge release of electricity. |