Tuesday, November 6, 2012

The Climate and Weather of Yellowstone


The climate and weather in Yellowstone National Park have often been called “unpredictable”.  Understanding the processes that create weather can help decipher the seemingly random patterns. The words climate and weather are often used interchangeably, however they are very different. Climate is the average of the weather conditions over a long period of time; weather is the current conditions of the area.

     One of the most important physical features of Yellowstone that contributes to the climate is its location. Continentality explains how a location's interior remoteness from the sea can affect temperature and climate. Land surfaces heat faster and cool faster than water. This is why locations near the coast have less temperature variations then land locked locations. Yellowstone is located inland, and also has a wide range of temperatures. The lowest temperature recorded was -66 degrees Fahrenheit, while the summer average is around 70 to 80 degrees Fahrenheit. (Wikipedia).
 
(This image shows the coast lines and their warmer temperatures. The darker colors show colder temperatures. Image courtesy of Google Images).

            Another reason for the drastic temperature differences in Yellowstone is its altitude. Yellowstone’s average altitude is 8,000 feet (Wikipedia). Higher elevations tend to be colder because there is less pressure from the atmosphere. Locations that are at sea level have more pressure from the atmosphere, pressing on the air molecules making the air more dense (Earth’s Temperature and Climate Lecture). The denser the air, is the more heat is transferred between molecules, making the surrounding area warmer. If a location is at a higher altitude the molecules are less compacted and less heat gets transferred. These two phenomena are the same across the globe, but there are other processes that affect climate on a local scale.

 
(This graph shows the temperature diffrence between a mountain top and the coast. Image courtesy of Google Images).


     The Rocky Mountains cut across Yellowstone and are largely responsible for the wind. As warm, moist air rises on the windward side of the mountains, the moisture condenses and rains. Having lost most of the moisture on one side of the mountain the air temperature rises and flows down the leeward side (Weather Lecture). This is how the Chinook winds are created, and is the reason why hikers who are unprepared with a wind breaker can suffer hypothermia from the wind chill.


(This diagram shows how the Chinook winds form. Image courtsey of Google Images).
Sources

Earth's Tempture and Climate Lecture
Weather Lecture