Weather

Weather is the state of the atmosphere at a given time and place. Most weather takes place in the troposphere, the lowest layer of the atmosphere.

Weather is described in a variety of ways by meteorologists, scientists who study and predict weather. Air temperature and pressure, the amount and type of precipitation, the strength and direction of wind, and the types of clouds are all described in a weather report.

Weather changes each day because the air in our atmosphere is always moving, redistributing energy from the Sun. In most places in the world, the type of weather events expected vary through the year as seasons change.  While weather can change rapidly, climate changes slowly, over decades or more, in response to changes in the factors that determine our climate. 

<a href="/earth/Atmosphere/clouds/kelvin_helmholtz.html&edu=high&dev=1">Kelvin-Helmholtz</a> clouds resemble breaking <a href="/earth/Water/ocean_waves.html&edu=high&dev=1">waves in the ocean</a>. They are usually the most developed near mountains or large hills. Wind deflected up and over a barrier, like a mountain, continues flowing through the air in a wavelike pattern. Complex <a href="/earth/Water/evaporation.html&edu=high&dev=1">evaporation</a> and <a href="/earth/Water/condensation.html&edu=high&dev=1">condensation</a> patterns create the capped tops and cloudless troughs of the waves. This image was taken on February 9, 2003 in the morning in Boulder, Colorado.<p><small><em> Courtesy of Roberta Johnson</em></small></p>A <a href="/earth/Atmosphere/tornado.html&edu=high&dev=1">tornado</a> begins in a severe <a href="/earth/Atmosphere/tstorm.html&edu=high&dev=1">thunderstorm</a> called a <a href="/earth/Atmosphere/tstorm/severe.html&edu=high&dev=1">supercell</a>.</p> The wind coming into the storm starts to swirl and forms a funnel. The air in the funnel spins faster and faster and creates a very <a href="/earth/Atmosphere/low_pressure.html&edu=high&dev=1">low pressure</a> area which sucks more This tornado was photographed in Carteret County, NC on June 7, 2004.<p><small><em>Courtesy of National Weather Service Forecast Office of Newport/Morehead City, NC</em></small></p>This photograph of a <a href="/earth/Atmosphere/clouds/cumulonimbus.html&edu=high&dev=1">cumulonimbus cloud</a> was taken on the <a href="/earth/grassland_eco.html&edu=high&dev=1">grasslands</a> of eastern Wyoming. Notice the <a href="/earth/Atmosphere/precipitation/rain.html&edu=high&dev=1">rain</a> and <a href="/earth/Atmosphere/precipitation/hail.html&edu=high&dev=1">hail</a> falling from this cloud! Cumulonimbus clouds form during <a href="/earth/Atmosphere/tstorm.html&edu=high&dev=1">thunderstorms</a>, when very warm, moist air rises into cold air. As this humid air rises, water vapor <a href="/earth/Water/condensation.html&edu=high&dev=1">condenses</a>, and forms huge <a href="/earth/Atmosphere/clouds/cumulonimbus.html&edu=high&dev=1">cumulonimbus</a> clouds.<p><small><em> Photo courtesy of <a href="http://www.inclouds.com">Gregory Thompson</a></em></small></p>Greenland's <a href="http://www.windows2universe.org/earth/polar/cryosphere_glacier1.html">ice sheet</a> saw a record <a href="http://www.windows2universe.org/headline_universe/olpa/greenland_10dec07.html">melt</a> in July 2012. Scientists studying this event have found that this melting event was triggered by an influx of unusually warm air and amplified by the presence of a blanket of thin low-level <a href="http://www.windows2universe.org/earth/Atmosphere/cloud.html">clouds</a> which pushed temperatures up above freezing. For more information see the <a href="http://www.news.wisc.edu/21638">press release</a> from the University of Wisconsin Madison.<p><small><em>Image courtesy of University of Wisconsin-Madison</em></small></p>On May 20, 2013, a massive EF5 <a href="http://www.windows2universe.org/earth/Atmosphere/tornado.html">tornado</a> hit Moore, Oklahoma, devastating communities and lives. The tornado, on the ground for 40 minutes, took a path through a subdivision of homes, destroying block after block of homes, and hitting two elementary schools just as school was ending as well as a hospital. Hundreds of people were injured, and 24 were killed.<p><small><em>Image courtesy of Ks0stm, Creative Commons Attribution-Share Alike 3.0 Unported license</em></small></p>Does Earth science matter? The power outage experienced by residents in New York City on 10/30/2012 due to Hurricane Sandy demonstrates the interconnectedness of our society, and the power of the Earth system. Every person should have an understanding of how the Earth system works so they can live better lives, protect those they love, and make wise choices. Earth science education is critical!<p><small><em>Image courtesy of Hybirdd, licensed under the Creative Commons Attribution-Share Alike 2.0 Generic license.</em></small></p>

Explore Weather

Weather Fronts

When a front passes over an area, it means a change in the weather. Many fronts cause weather ...Read more

Clouds

Clouds can come in all sizes and shapes, and can form near the ground or high in the atmosphere. ...Read more

Thunderstorms

Thunderstorms are one of the most thrilling and dangerous types of weather phenomena. Over ...Read more

Tornadoes

Tornadoes form from severe thunderstorms. They have a very high energy density which means ...Read more

Hurricanes

As a strong hurricane heads towards a vulnerable coast, people take precautions - boarding ...Read more

Heat Waves

It’s the middle of the summer and it’s hot – hotter than normal. The heat lasts for days. It’s ...Read more

Blizzards

Fast winds blowing up to 75 mph (120 kph), 43 inches (1 meter) of snowfall, power outages, ...Read more

Urban Weather

Cities can affect the weather. Looking at satellite data, scientists have observed that heavy ...Read more

Atmospheric Optics

Have you ever seen clouds in the sky that looked different than "normal" clouds? Or have you ...Read more

Weather Instruments

Knowing what weather is on the way is important to many people. For example, farmers plan their ...Read more

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Did you know?

Did you know that you can now share your poems about our collection of cloud art photos. Have fun!

Did you know that the upper atmosphere of the Earth overlaps with the Earth's ionosphere?

 

Earth and Space Science Concept of the Day

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Salinity
xSalinity : The percent of salt in saltwater

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Research Highlights

Unprecedented Warming in East Africa's Lake Tanganyika

Lake Tanganyika, the second-oldest and second-deepest lake in the world, could be in for some rough waters. Geologists have determined that the East African rift lake has experienced unprecedented warming...Read more


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