Weather A - Z (D-E)

Learn more about the weather in the learning room.
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Weather A - Z (D-E)

Post by ICE » Fri Apr 28, 2006 9:55 am

Dense Fog - Its fog that reduces horizontal visibility to 1/4 mile or less. Dense fog usually creates traveling problems and delays.

Dense Fog Advisory - It’s issued when dense fog covers a widespread area and reduces visibility to ¼ of a mile or less.

Dew - Water that forms on objects close to the ground when its temperature falls below the dew point of the surface air.

Dew Point - The temperature at which water starts to condense out of a particular air mass. The dew point temperature changes only when the moisture content of the air changes. The higher the dew point, the greater the moisture content is in the air.

Disturbance - A low pressure system, a tropical area of storminess, or any area in which the weather is in a state of cloudiness, precipitation or wind.

Downburst - A strong downward rush of air, which produces a blast of damaging, winds on or close to the surface.

Drifting Snow - An uneven amount of snowfall or existing snow on the ground caused by strong winds. Drifting snow can be very dangerous for drivers.

Drizzle - Light rain consisting of water droplets that are very small.

Drought - A period when a region has a lack of rainfall. Droughts can affect a fairly small area for a season or an entire continent for years. Too little rainfall can cause shortages in the water supply, destroy crops, and cause widespread hunger. Droughts also dry up soil, which then gets picked up by the wind and causes dust storms.

Dry Line - A boundary that separates warm, dry air from warm, moist air. The differences in the two air masses may be significant. The dry line is usually a boundary where thunderstorms form.

Dust Devil - Small whirlwinds of dust that form in dry areas like deserts. They may look like tornadoes, but dust devils are not formed by thunderstorms and do not drop from the sky. Dust devils are caused by swirling winds that rise with the warm air found over the ground.

Earth - The third planet from the sun and is our home.

Earthquake - The shaking or movement of a portion of the Earth's surface.

El Niño - The unusual warming of the surface waters of the eastern tropical Pacific Ocean. It causes changes in wind patterns that have major effects on weather all across the globe.

Environment - The external conditions and surroundings, especially those that affect the quality of life of plants, animals and human beings.

Equator - The imaginary great circle of 0 degrees latitude on the Earth's surface, separating the Northern Hemisphere from the Southern Hemisphere.

Erosion - The wearing away of the Earth’s surface by the action of the sea, running water, moving ice, precipitation or wind.

Evaporation - The process of changing a liquid (like water) to a vapor. It’s the opposite of condensation.

Excessive Heat Warning - It’s issued within 12 hours of the onset of the heat conditions listed in the excessive heat watch.

Excessive Heat Watch - It’s issued when the following conditions occur within 12-36 hours: a heat index of at least 105 degrees for more than 3 hours per day for 2 consecutive days or a heat index more than 115 degrees for any period of time.

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