Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Meteorology and You Common Core State Standard: ELA: Reading Informational Text (3.1-10 through 8.1-10) AIR MASSES AND COLD FRONTS Here in the northeast, we know very well what cold fronts can do. They have brought us some of our most turbulent weather, ranging from severe thunderstorms to a deep freeze. A front is the boundary between two air masses, and in the case of a cold front, it is when cold air pushes into an area at a fairly quick pace. AIR MASSES Think of an air mass as a very large bubble. They are several hundred miles across, and they each have different characteristics. There are several different classifications for air masses. Here are the predominant ones: • Maritime Tropical - warm and wet • Maritime Polar - cool and wet • Continental Tropical - warm and dry • Continental Polar - cool and dry During the winter, a maritime polar air mass would give us the best opportunity to see a snow storm, while a continental polar air mass would give us dry and cold weather. Maritime air masses are typically wetter than continental air masses. Polar air masses are colder than Tropical ones, and vice versa. If you have a continental polar air mass pushing up against a maritime tropical air mass, the cold front between those two would be a strong one. COLD FRONTS Have you ever been outside during the summer on a hot and humid day, and all of a sudden a line of thunderstorms comes seemingly out of nowhere? That very well could have been due to a cold front moving through the area. Severe weather is caused by rising air in the atmosphere, and a cold front causes just that. When the front approaches, it literally forces the air to rise, leading to condensation. A cold front typically brings a narrow band of rain <http://en.wikipedia.org/wiki/Precipitation (meteorology)> that follows along the leading edge of the cold front. These bands of rain can bring severe thunderstorms, especially during the spring and autumn months, when the difference in temperature is higher. One way to know when a cold front has come through is not only the cooler temperatures, but also a shift in the wind direction. The wind will typically come out of the south before the front, and from the north/northwest after the front moves through. Next time you watch a local weathercast, look to see if the weather person mentions any fronts. If they do, try to find the air masses! Did You Know Cold fronts move faster than warm fronts, sometimes as much as 20 mph faster. This is because the cold air behind the cold front is heavier and denser than the warm air behind the warm front. The heavier, denser, cold air can push the warmer lighter air ahead of the cold front out of the way much easier than the warm air can push the cold air ahead of the warm front. When a cold front comes through, the temperature can change drastically, sometimes as much as 30 degrees in only a few hours! That’s why sometimes in New England it can feel like we went from summer to fall in one day. When a cold front catches up to the warm front, it will overtake the warm front and become occluded. This is usually towards the end of a storm’s life cycle, and it signals that any strong weather will be weakening soon. Lightning Quick Activity Look at a weather map on the National Weather Service’s website (weather.gov), and try to find the different air masses. Can you see the tropical air mass in the southern United States? Can you see the polar air in the northern part of the country? Are there any noticeable fronts on the map? Search this site to find the explanation! http://www.weatherwizkids.com/weather-forecasting.htm