Air moves into a Low pressure system. It pushes any air that was there upwards.
Click on image for full size
Windows to the Universe original image

Low Pressure Systems

Have you ever seen a weather map with a red L on it? This red L means there is a low pressure system over that area of the map. Just what does that mean?

It means that that area has lower pressure then the air around it.

When there is a Low above your house, you should expect cloudy skies and maybe even rain or snow! The way I remember it is that a Low will make me feel low because "bad" weather is on the way...

Last modified April 19, 2009 by Jennifer Bergman.

Shop Windows to the Universe Science Store!

The Fall 2009 issue of The Earth Scientist, which includes articles on student research into building design for earthquakes and a classroom lab on the composition of the Earth’s ancient atmosphere, is available in our online store.

Windows to the Universe Community

News

Opportunities

You might also be interested in:

Traveling Nitrogen Classroom Activity Kit

Check out our online store - minerals, fossils, books, activities, jewelry, and household items!...more

Measuring Atmospheric Pressure

Even though we can't see air, it is real and pushes on the things it surrounds. The push of the atmosphere is called pressure. Atmospheric pressure changes all the time. We can measure the pressure of...more

When and Where Will a Hurricane Form?

In some years there are many hurricanes. Other years there are only a few. Each year, scientists make predictions about what they think the hurricane season will be like. They can’t say for sure how many...more

Examples of Advisories, Watches, and Warnings for Weather Events

Below is a list of different weather advisories, watches, and warnings. Severe Thunderstorm Watch: A severe thunderstorm watch is issued when a thunderstorm with strong winds and/or hail the size of a...more

Type of Wind: Northeaster

Northeasters, also known as nor’easters, are cold winds that can bring heavy snow or sleet. These winds blow from 40-55 mph (64.5-88.7 kph). They are classified as gale winds. Most snowstorms in the eastern...more

Sea Level

Sea level is the height of the ocean surface. Scientists measure sea level to figure out how much sea level rise is happening now because of global warming. If you tried to draw a flat line at the top...more

Walker Circulation

The Walker circulation is an ocean-based system of air circulation. This system influences weather on the Earth.  Normally, the warm, wet western Pacific Ocean is under a low pressure system, and the cool...more

Barometer

A barometer is a weather instrument used to measure atmospheric pressure. There are two types of barometers used to do this: the mercury barometer and with an aneroid barometer The mercury barometer was...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA