Weather Factors Key Terms
Condition of the atmosphere at a specific time and place
Weather
High pressure center in the northern hemisphere with winds blowing clockwise outward from the middle causing clear skies
Anticyclone
Low pressure center in the northern hemisphere with winds blowing counterclockwise toward the middle causing clouds and precipitation
Cyclone
Side or direction from which the wind blows
Windward
Deflection or curving of winds and ocean currents due to the rotation of the earth
Coriolis Effect
Fast moving west-to-east flowing “river” of air high in the troposphere that influences weather
Jet Stream
Upward movement of air as it passes over a mountain range
Orographic Lifting
Opposite side or direction from which the wind blows
Leeward
Movement of air along earth’s surface
Wind
Air that moves up and down
Air Current
Line on a map connecting points of equal air pressure
Isobar
Line on a map connecting points of equal temperature
Isotherm
Measure of how much water vapor is in the air compared to how much water vapor the air can hold at that temperature
Relative Humidity
Measure of the amount of thermal (heat) energy
Temperature
Energy added or removed from a substance in order for it to change its state of matter
Latent Heat
Temperature at which condensation occurs
Dew Point
The weight of air pressing on a surface
Air Pressure
Change from a gas to a liquid
Condensation
Change from a liquid to a gas
Evaporation
Change from a gas directly to a solid
Deposition
Change from a solid directly to a gas
Sublimation
Boundary between two large masses of air with different temperatures
Front
The change in a measurement over a given horizontal distance
Gradient
Coastal wind blowing during the night from the land toward the ocean
Land breeze
Coastal wind blowing during the day from the ocean toward the land
Sea breeze
Holding as much water as is possible
Saturated
Low, flat, expansive, blanket-like clouds
Stratus
Gray, thick blanket-like clouds that bring rain
Nimbostratus
Clouds along the ground
Fog
White, fluffy, cotton ball – like clouds that mean fair weather
Cumulus
High, feather clouds made of ice crystals
Cirrus
Tall, anvil-shaped clouds that form during thunderstorms; thunderhead clouds
Cumulonimbus
Instrument used to measure wind speed
Anemometer
Instrument used to measure wind direction
Wind Vane
Instrument used to measure air pressure
Barometer
Instrument used to measure temperature
Thermometer
Instrument used to measure relative humidity
Psychrometer
Instrument used to measure the amount of precipitation
Rain Gauge
Rain, snow, sleet, hail
Precipitation
Precipitation in which raindrops freeze as they fall to earth; above freezing in clouds but below freezing at ground level
Sleet
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
Hail
Precipitation in which raindrops freeze after they hit the ground; above freezing in clouds but below freezing at ground level
Freezing Rain
Precipitation in which water vapor condenses directly into ice crystals in the clouds which fall to the surface; below freezing in clouds
Snow
Precipitation in which liquid drops of water fall from clouds. It is above freezing in clouds and at ground level
Rain
Condition of the atmosphere at a specific time and place
Weather
High pressure center in the northern hemisphere with winds blowing clockwise outward from the middle causing clear skies
Anticyclone
Low pressure center in the northern hemisphere with winds blowing counterclockwise toward the middle causing clouds and precipitation
Cyclone
Side or direction from which the wind blows
Windward
Deflection or curving of winds and ocean currents due to the rotation of the earth
Coriolis Effect
Fast moving west-to-east flowing “river” of air high in the troposphere that influences weather
Jet Stream
Upward movement of air as it passes over a mountain range
Orographic Lifting
Opposite side or direction from which the wind blows
Leeward
Movement of air along earth’s surface
Wind
Air that moves up and down
Air Current
Line on a map connecting points of equal air pressure
Isobar
Line on a map connecting points of equal temperature
Isotherm
Measure of how much water vapor is in the air compared to how much water vapor the air can hold at that temperature
Relative Humidity
Measure of the amount of thermal (heat) energy
Temperature
Energy added or removed from a substance in order for it to change its state of matter
Latent Heat
Temperature at which condensation occurs
Dew Point
The weight of air pressing on a surface
Air Pressure
Change from a gas to a liquid
Condensation
Change from a liquid to a gas
Evaporation
Change from a gas directly to a solid
Deposition
Change from a solid directly to a gas
Sublimation
Boundary between two large masses of air with different temperatures
Front
The change in a measurement over a given horizontal distance
Gradient
Coastal wind blowing during the night from the land toward the ocean
Land breeze
Coastal wind blowing during the day from the ocean toward the land
Sea breeze
Holding as much water as is possible
Saturated
Low, flat, expansive, blanket-like clouds
Stratus
Gray, thick blanket-like clouds that bring rain
Nimbostratus
Clouds along the ground
Fog
White, fluffy, cotton ball – like clouds that mean fair weather
Cumulus
High, feather clouds made of ice crystals
Cirrus
Tall, anvil-shaped clouds that form during thunderstorms; thunderhead clouds
Cumulonimbus
Instrument used to measure wind speed
Anemometer
Instrument used to measure wind direction
Wind Vane
Instrument used to measure air pressure
Barometer
Instrument used to measure temperature
Thermometer
Instrument used to measure relative humidity
Psychrometer
Instrument used to measure the amount of precipitation
Rain Gauge
Rain, snow, sleet, hail
Precipitation
Precipitation in which raindrops freeze as they fall to earth; above freezing in clouds but below freezing at ground level
Sleet
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
Hail
Precipitation in which raindrops freeze after they hit the ground; above freezing in clouds but below freezing at ground level
Freezing Rain
Precipitation in which water vapor condenses directly into ice crystals in the clouds which fall to the surface; below freezing in clouds
Snow
Precipitation in which liquid drops of water fall from clouds. It is above freezing in clouds and at ground level
Rain