November 13-19 is the National Geographic Society's Geography Awareness Week. This year's theme is The Adventure in Your Community. Geography is all around us and varies from region to region in the United States. Did you know that geography and weather are very closely linked? Explore some of the connections below.
- Pacific Northwest: There are several volcanoes in the Pacific Northwest, including Mount St. Helens, Mount Rainier and Mount Hood. Volcanic eruptions can impact local weather. Eruptions emit particles and gases into the atmosphere, creating a haze. This haze can remain in the air for years, reflecting the sun's rays and reducing temperatures at the Earth's surface.
- Western US: The Sierra Nevada Mountains that run north-south through California basically separate the Western United States into a wetter (west) side and a drier (east) side. Storms come off the Pacific Ocean from the west and get lifted up by the Sierra Nevada Mountains – a process called orographic lifting. As these storms rise, they cool and condense, raining a lot of water back onto the ground. But, as the storms continue to make their way over the top of the mountains to the east, they don't dump as much rain because they have already lost a lot of moisture. This causes a rain shadow to form on the east side of the mountain range where there is a low amount of rainfall. The rain shadow from the Sierra Nevada and Cascade Mountains impacts the weather in the Great Basin, which covers most of Nevada and parts of Utah.
- Great Lakes: The Great Lakes region is known for its lake effect snow. As cold air passes over the Lakes, warmer lake water below evaporates and heats the bottom layer of cold air. Warm, moist air rises and cools, causing condensation and cloud formation. If humidity is high enough and temperatures are cold enough, snow falls. Winds push these clouds over land, where increased friction slows the winds, leading to more snowfall accumulation. As winds move farther inland and encounter hills, rising air cools even more, creating even more snow!
- Great Plains: The Great Plains may be known as Tornado Alley, but their topography allows for another weather phenomena – blizzards! The Rocky Mountains to the west are the driving force for blizzards in the Great Plains. A cold polar air mass that moves off the Rockies pushes southward accompanied by high winds, intense cold and considerable amounts of snow that can last for several days.
- South Central US: Droughts are periods of unusually dry weather that the South Central United States experiences at times – including right now. Droughts can bring upon dust storms, which are common in arid and semi-arid regions. A dust storm occurs when a gust of wind blows loose sand or dust particles off the ground, breaks down the particles and keeps them suspended in the air. Dust storms can spread over hundreds of miles and well over 10,000 feet into the air.
- Eastern US: One geographic feature that affects the entire East Coast is the Atlantic Ocean. The ocean plays a big role in determining the temperatures near the coast. During fall and winter when the ocean is warmer than the land, the coastal regions experience warmer temperatures than inland areas. In the springtime, ocean breezes keep temperatures along the coast cooler than inland areas.
Learn more about Geography Awareness Week: www.nationalgeographic.com/geography-action/index.html.
(Sources: National Science Teachers Association, "Earthquakes, Volcanoes, and Tsunamis", http://www.enviroliteracy.org/nsfmod/NaturesFury.pdf, "A Rain Shadow", http://bcs.whfreeman.com/thelifewire/content/chp56/5602001.html, "Warm water helps create Great Lakes snowstorms." University Corporation for Atmospheric Research. 2008, US Department of State, "The Great Plains and Prairies", http://countrystudies.us/united-states/geography-17.htm, Kidz World, "Dust Storms", http://www.kidzworld.com/article/707-dust-storm-on-the-loose, "Cold air damming can bring ice to East." http://www.usatoday.com/weather/tg/wcolddam/wcolddam.htm, "Warm water helps create Great Lakes snowstorms." University Corporation for Atmospheric Research. 2008., United States Search and Rescue Task Force, "Predicting Weather", http://www.ussartf.org/predicting_weather.htm)
