31 terms

7th Grade Science: Weather 1-3 and 1-4 winds and moisture

Science 7 Vocabulary for Weather modules 3 and 4 Winds Moisture in the Air
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anemometer
instrument that measures wind speed
wind vane
instrument that determines the direction of the wind
Global Winds
General wind patterns that occur over the whole Earth.
Caused by uneven heating of Earth's surface and Earth's rotation (the Coriolois Effect).
Examples are Polar Easterlies, Mid Latitude Westerlies, Tropical Easterlies (trade winds)
also called "prevailing winds"
Global Pressure Belts
0° & 60° Low Pressure (humid rising air with rain)
0° = doldrums
30° & 90° High Pressure (dry sinking air with deserts)
30° = horse latitudes
regional winds
winds that occur over hundreds of miles like monsoons
local winds
winds that occur over a few miles like land and sea breezes
Wind Sock
truncated cloth cone used to indicate wind direction
cloud
general term for a mass of tiny liquid water droplets suspended in the atmosphere by air currents
Cirrus
a wispy white cloud (usually of fine ice crystals) at a high altitude (4 to 8 miles)
Cirrocumulus
high altitude ice crystal cloud consisting of a series of regularly arranged small clouds resembling ripples
Cirrostratus
high altitude ice crystal cloud in a large thin layer.
Stratus
Clouds that form in low, horizontal layers, cover all or most of sky. Can cause precipitation.
Altostratus
Greyish/bluish cloud sheet or layer of striated mid-level clouds. Parts cover the sky and sun (overcast), can see the sun vaguely like translucent and makes it dim; has holes in the clouds; does not indicate bad weather
Nimbostratus
Clouds that are low-level, uniform layer, usually very dark, that bring steady precipitation
Cumulus
Thick, fluffy clouds with flat bases, formed by vertically rising air currents. Sometimes (not usually) cause precipitation.
Cumulonimbus
A "towering" cloud of vertical development when thunderstorms occur. Often has a flat top called an "anvil".
Fog
A stratus cloud located on or near the ground. Occurs when temperature drops to the dew point.
Smog
A combination of smoke and fog
visibility
how far we can see
evaporation
process by which water molecules enter the air in the gaseous state (called water vapor)
humidity
general term for the presence of water vapor in the air
specific humidity
the actual grams of water vapor in the air.
relative humidity
amount of water vapor in the air compared to the maximum amount that can be held at that temperature. Expressed as "percent"
(a ratio of some number/100).
precipitation
water vapor that has condensed and falls to Earth as rain, sleet, hail or snow.
rain
Forms from water droplets pulled to Earth by gravity, or ice crystals melting as they fall.
sleet
A type of winter precipitaiton that occurs when a snowflake partially melts then re-freezes as an ice pellet or ball. These pellets do not grow in size so are generally less than 1/4 inch.
hail
Chunks of ice formed in cumulonimbus clouds by strong updrafts of wind. These pellets often have many layers of ice and can be more than 1/2 inch to many inches in diameter.
Hair Hygrometer
Instrument based on the change in length of horse hair responding to changes in humidity.
Psychrometer
an instrument for measuring humidity consisting of a dry-bulb thermometer and a wet-bulb thermometer.
rain gauge
A tool that measures how much rain has fallen.
dew point
The temperature at which condensation begins
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