Weather Factors Key Terms

Weather

Weather

Condition of the atmosphere at a specific time and place

Anticyclone

High pressure center in the northern hemisphere with winds blowing clockwise outward from the middle causing clear skies

Cyclone

Low pressure center in the northern hemisphere with winds blowing counterclockwise toward the middle causing clouds and precipitation

Windward

Side or direction from which the wind blows

Coriolis Effect

Deflection or curving of winds and ocean currents due to the rotation of the earth

Jet Stream

Fast moving west-to-east flowing “river” of air high in the troposphere that influences weather

Orographic Lifting

Upward movement of air as it passes over a mountain range

Leeward

Opposite side or direction from which the wind blows

Wind

Movement of air along earth’s surface

Air Current

Air that moves up and down

Isobar

Line on a map connecting points of equal air pressure

Isotherm

Line on a map connecting points of equal temperature

Relative Humidity

Measure of how much water vapor is in the air compared to how much water vapor the air can hold at that temperature

Temperature

Measure of the amount of thermal (heat) energy

Latent Heat

Energy added or removed from a substance in order for it to change its state of matter

Dew Point

Temperature at which condensation occurs

Air Pressure

The weight of air pressing on a surface

Condensation

Change from a gas to a liquid

Evaporation

Change from a liquid to a gas

Deposition

Change from a gas directly to a solid

Sublimation

Change from a solid directly to a gas

Front

Boundary between two large masses of air with different temperatures

Gradient

The change in a measurement over a given horizontal distance

Land breeze

Coastal wind blowing during the night from the land toward the ocean

Sea breeze

Coastal wind blowing during the day from the ocean toward the land

Saturated

Holding as much water as is possible

Stratus

Low, flat, expansive, blanket-like clouds

Nimbostratus

Gray, thick blanket-like clouds that bring rain

Fog

Clouds along the ground

Cumulus

White, fluffy, cotton ball-like clouds that mean fair weather

Cirrus

High, feather clouds made of ice crystals

Cumulonimbus

Tall, anvil-shaped clouds that form during thunderstorms; thunderhead clouds

Anemometer

Instrument used to measure wind speed

Wind Vane

Instrument used to measure wind direction

Barometer

Instrument used to measure air pressure

Thermometer

Instrument used to measure temperature

Psychrometer

Instrument used to measure relative humidity

Rain Gauge

Instrument used to measure the amount of precipitation

Precipitation

Rain, snow, sleet, hail

Sleet

Precipitation in which raindrops freeze as they fall to earth; above freezing in clouds but below freezing at ground level

Hail

Precipitation in which strong winds repeatedly blow raindrops up high in clouds where a new layer of frost forms forming a small to large ball of ice which falls to earth

Freezing Rain

Precipitation in which raindrops freeze after they hit the ground; above freezing in clouds but below freezing at ground level

Snow

Precipitation in which water vapor condenses directly into ice crystals in the clouds which fall to the surface; below freezing in clouds

Rain

Precipitation in which liquid drops of water fall from clouds. It is above freezing in clouds and at ground level