Weather is the state of the atmosphere at a place and time: temperature, rainfall, wind, cloud and air pressure. An air mass is a huge body of air with similar temperature and moisture, such as cold dry air from the poles or warm moist air from the tropics. Where two air masses meet is a front. At a cold front, cold air pushes under warm air and lifts it quickly, giving heavy showers and a drop in temperature.
High pressure usually brings settled, dry weather: clear skies, hot in summer and frosty in winter. Low pressure usually brings clouds, wind and rain. Wind blows from high pressure towards low pressure. Weather forecasters use satellites, weather stations and computer models to predict the weather.
Worked example
A barometer shows falling pressure. What weather is likely?
- Falling pressure means a low-pressure area is coming.
- Low pressure means rising air that cools and forms clouds.
Answer:Cloudy, windy and wet weather is likely.
Key words
- air pressure
- the push of the air on a surface
- air mass
- a large body of air with similar temperature and moisture
- front
- the boundary between two air masses
- barometer
- an instrument that measures air pressure
New questions every time.
NGSS-referenced: MS-ESS2-5