Weather Unit Vocabulary

Weather- State of the atmosphere at a given time and place; it is described by wind, temperature, cloud cover, moisture in the form of humidity and/or precipitation, and air pressure; weather changes daily, hourly, and seasonally

Meteorologist- A scientist who studies weather

Sun- Warms the air, water, and land of Earth

temperature- measurement in degrees warm or cold; influenced by cloud cover (i.e., generally cooler on cloudy days); measured by a thermometer in degrees Fahrenheit or Celcius

Wind speed-Changes as air pressure changes; how fast the wind is blowing; measured by an anemometer

Wind direction- Reported by the direction from which the wind originates; indicated by a wind vane

Precipitation- Form of water (rain, snow, ice, sleet, hail) that falls from the clouds to Earth; can be measured by a rain gauge

Air pressure- Also known as barometric pressure, it is the weight of the air above the surface of the Earth; it is measured by a barometer

Cloud cover- Fraction of the sky covered by cloudy; data is collected by observation and reported as cloudy, partly cloudy, partly sunny, or clear.

Data- Information

Hemisphere- Half of a sphere; the Earth is divided into the Northern and Southern Hemispheres by the equator; (Earth is also divided into the Eastern and Western Hemispheres by the Prime Meridian)

Equator- Imaginary line around the middle of the Earth; assigned 0° latitude

Latitude- The distance north or south of the equator; for example, Raleigh, NC is located at approximately 36°N, which indicates it location North of the equator

Longitude- The distance east or west of the Prime Meridian

Angle of incidence- Angle that sunlight reaches the surface of the Earth; sometimes called the angle of insolation

Direct sunlight- Sun rays that strike the Earth with more intensity near the equator

Indirect sunlight- Sun rays that strike the Earth with less intensity due to the tilt of the Earth and the curvature of its surface.

Tilt of the Earth- Earth is tilted on its axis at 23.5°; this is the main reason there are seasons on Earth

Rotation- Spin; Earth rotates on its axis; one rotation of Earth is approximately 24 hours (1 day)

Revolution- Orbit; Earth revolves around the Sun in an elliptical orbit; one revolution around the Sun is approximately 365 days (1 year)

Seasons- Summer, autumn (fall), winter, and spring

Conduction- Transfer of thermal energy between objects that are touching.

Convection- Transfer of thermal energy by liquids or gases; land and water heat the air above through convection currents.

Current- Constant movement.

Elevation- The height of something

Gulf Stream- A warm water surface current in the Atlantic Ocean that moves from the southern tip of Florida up the East Coast then across the Atlantic (a visual is shown in the StudyJam about Waves and Currents )

Radiation- Transfer of thermal energy by electromagnetic waves through places without matter; the Sun’s radiation warms Earth’s air, land, and water.

Convection- Transfer of thermal energy by liquids or gases; land and water heat the air above through convection currents.

Elevation-  The height of something

Mountain- A very tall, high, natural place on Earth’s surface.

Radiation- Transfer of thermal energy by electromagnetic waves through places without matter; the Sun’s radiation warms Earth’s air, land, and water.

Sea level-  Where the ocean meets the land; assigned zero elevation.

Condensation- Changing from water vapor to a liquid.

Evaporation- Changing from liquid to a water vapor

Precipitation- Form of water that falls from clouds to Earth

Run-off- Excess water from falling precipitation or melting precipitating that the soil cannot absorb

Transpiration- Water evaporating from the leaves of plants

Water cycle- Continuous process of water moving from the Earth’s surface to the atmosphere and back to Earth

Water vapor- Water in a gas state

Cloud- A large collection of tiny water droplets or ice crystals in the atmosphere

Cirrus- High level clouds that look thin and wispy, like feathers; means “curl of hair”; indicate fair to pleasant weather

Cumulus- Middle level clouds that look puffy like cotton; means “heap” or “pile”; indicate fair weather

Stratus- Low level clouds that look like layers or a gray blanket that covers the sky; means to “spread out”; indicates overcast weather and sometimes produce precipitation; fog is a stratus cloud near the ground.

Wind- Air moving  horizontally; caused by uneven heating and cooling of the Earth’s surface

Local Wind- Moves across small distances close to Earth’s surface; examples include sea breezes and land breezes

Global wind- Moves across great distances above the Earth; these wind patterns are stable and predictable; examples include Polar Easterlies, Prevailing Westerlies, and Trade Winds

Trade Winds- Winds that blow East to West toward the equator between 30° N latitude and 30° S latitude; can impact North Carolina weather by moving a hurricane toward the Southeastern United States

Prevailing Westerlies- Winds that blow West to East toward the poles in both hemispheres between 30° and 60° latitudes; impacts North Carolina weather by moving weather systems from the West toward North Carolina

Land breeze- A convection current where air flows from land to sea during the night (a result of land heating and cooling at a faster rate than water)

Sea breeze- A convection current where air flows from sea to land during the day (a result of land heating and cooling at a faster rate than water)

Jet stream- A current in the atmosphere located over North America that moves West to East; it changes position North or South seasonally; impacts North Carolina weather by moving weather systems from the West toward North Carolina; additionally its fluctuations to the North can bring warmer temperatures to North Carolina while its fluctuation to the South can bring cooler temperatures to North Carolina.

Air mass- A large region of the atmosphere where the air has similar properties throughout such as temperature, humidity, and air pressure.

High pressure system- A whirling mass of cool, dry air; because cool air is more dense than warm air, it sinks. High pressure brings fair weather, sunny skies and light winds. High pressure systems rotate clockwise.

Low pressure system- A whirling mass of warm, moist air; because warm air is less dense than cool air, it rises and cooler (more dense) air flows underneath. Low pressure brings storms, strong winds, and changing weather. Low pressure systems rotate counter-clockwise (like hurricanes in the Atlantic).

Front- A boundary between warm and cold air masses

Cold front- A boundary between two air masses (one warm, one cold) moving so that the colder air replaces the warmer air

Warm front- A boundary between two air masses (one warm, one cold) moving so that the warmer air replaces the colder air

Stationary front- A boundary between two air masses (one warm, one cold) that more or less doesn’t move; a stationary front can wobble back and forth for several hundred miles a day

El Niño- A natural oscillation (shift) of the warmest surface water near the equator in the Pacific Ocean eastward toward South America; this impacts weather around the world.

La Niña- The surface water near the equator in the Pacific Ocean gets cooler; this impacts weather around the world.

Heat- Energy that exists in matter

Temperature- Measurement of heat; a high temperature indicates more thermal energy

Convection- Movement of thermal energy by the movement of liquids or gases

Conduction- Transfer of thermal energy between two objects that are touching

Radiation- Transfer of energy by electromagnetic waves through places with or without matter

Conductor- Any object that allows heat (energy) to pass through easily

Insulator- Any object that does not allow heat (energy) to pass through easily

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