Air Masses


Deserts, plains, and oceans typically cover large areas and contain relatively few topographical irregularities. In such regions, large masses of air can accumulate without being broken apart by mountains, land/water interfaces, and other features that would disturb the air mass. The absence of strong wind also favors the development of an air mass; hence, air masses cannot develop easily in regions where cyclonic or anticyclonic storms are common.

Clouds also form when air masses collide due to the air being forced upward. The type of front determines what clouds, precipitation, or storms may form. However, if the cloud changes into a cumulonimbus cloud, there will be a thunderstorm or snow depending on the temperature. A more complicated situation occurs when a cold front overtakes a slower-moving warm front to create an occluded front.

The air of cold air masses is more dense than warmer air masses. Therefore, as these cold air masses move, the dense air undercuts the warmer air masses forcing the warm air up and over the colder air causing it to rise into the atmosphere. Continental arctic – cA – formed around the North Pole … very cold and very dry. This air often forms when a high-pressure area forms over Eastern Alaska, the Yukon, Siberia or northern Canada, usually above the Arctic Circle. An air mass is a large body of air that, at any one height, has a relatively steady temperature and moisture content throughout. Air masses typically cover areas ranging from hundreds of thousands to millions of square miles.

Hurricanes are measured by the Saffir–Simpson hurricane wind scale , dividing storms into five categories distinguished by the intensities of their sustained winds . September 2022, Hurricane Fiona caused widespread destruction and power outages throughout Atlantic Canada. Fiona left more than 500,000 people without power, including 80% of all Nova Scotia customers and 95% of PEI customers.

What’s interesting about the characteristics of an air mass is that, not only do they describe the air mass, but they also tell you where you can find that air mass on Earth. Relatively large gradients in temperature and dew point characterize the zone where two contrasting air masses meet. So, fronts just don’t appear at the surface of the earth, they have a vertical structure or slope to them as well.

Required elements are warm, moist, unstable air, producing cumulonimbus clouds. If there is a very steep lapse rate – often as a cold front pushes in – very strong updrafts ladun blog and instability occur which, for some reason, occasionally spawn tornadoes. Severe thunderstorms have persistent updrafts that can reach speeds of 160 kmh.

An occluded front is represented on a weather map by means of a solid line that contains alternating triangles and half circles on the same side of the line. Certain locations on the Earth’s surface possess the topographical characteristics that favor the development of air masses. In such regions, large masses of air can accumulate without being broken apart by mountains , land/water interfaces, and other features that would break up the air mass.

As the jet stream changes intensity and position, it affects the motion and strength of air masses. Where air masses converge, they form boundaries called “fronts”. Once hurricanes hit land they weaken because of friction with the ground and because their fuel source disappears. However as the winds drop, precipitation often continues because so much moisture was evaporated and then condensed in the clouds. Lightning is created by the buildup of electrical energy within a cumulonimbus cloud or between the cloud and the ground. Within the cloud, rapidly moving air “rubs” together, creating electrical polarities.

Anticyclones rotate clockwise in the northern hemisphere and counter clockwise in the southern hemisphere. MT air masses are an important way by which heat from the tropics can move polewards. The southern part of the NW Atlantic high that exists during the summer brings cool easterlies into New England and locations further south. Anticlockwise flow around the cyclone draws in the cold mP air into the US, generally from the NE – called nor’easter. Processes that contribute to air modification is cooling from below, heating from below, evaporation of water, and limiting over mountains. The term front was suggested by the Bjerkneses because the collision of two air masses reminded them of a battlefront during a military operation.