When air masses meet - Eniscuola
Winds usually blow parallel to the front, but in opposite directions. Much of the weather occurs where at fronts where air masses meet. When two large air masses meet, the boundary that separates them is Stationary Fronts A stationary front occurs when the frontal boundary between appear as an alternating series of red semicircles and blue triangles drawn on opposite. When a moving cold air mass meets a warm air mass, that is lighter, it tends to wedge below the latter, thus giving origin to a cold front. The warm air is forced.
One letter, written in upper case, indicates the approximate latitude and, therefore, temperature of the region: A for arctic; P for polar; E for equatorial; T for tropical. The distinctions between arctic and polar on the one hand, and equatorial and tropical on the other are relatively modest. The first two terms arctic and polar refer to cold air masses, and the second two equatorial and tropical to warm air masses. A second letter, written in lower case, indicates whether the air mass forms over land or sea and, hence, the relative amount of moisture in the mass.
The two designations are c for continental land air mass and m for maritime water air mass. The two letters are then combined to designate both temperature and humidity of an air mass. One source region of arctic air masses, for example, is the northern-most latitudes of Alaskaupper Canadaand Greenland. Thus, air masses developing in this source region are designated as cA cold, land air masses.
- How Weather Works
Similarly, air masses developing over the Gulf of Mexicoa source region for maritime tropical air masses, are designated as mT warm, water air masses. The movement of air masses across the earth's surface is an important component of the weather that develops in an area. For example, weather patterns in North America are largely dominated by the movement of about a half dozen air masses that travel across the continent on a regular basis.
Two of these air masses are the cP and cA systems that originate in Alaska and central Canada and sweep down over the northern United States during the winter months.
High School Earth Science/Changing Weather - Wikibooks, open books for an open world
These air masses bring with them cold temperatures, strong winds, and heavy precipitationsuch as the snowstorms commonly experienced in the Great Lakes states and New England. The name "Siberian Express" is sometimes used to describe some of the most severe storms originating from these cP and cA air masses. From the south, mT air masses based in the Gulf of Mexicothe Caribbean, and western Atlantic Ocean move northward across the southern states, bringing hot, humid weather that is often accompanied by thunderstorms in the summer.
Weather along the western coast of North America is strongly influenced by mP air masses that flow across the region from the north Pacific Ocean.
These masses actually originate as cP air over Siberiabut are modified to mP masses as they move over the broad expanse of the Pacific, where they often pick up moisture. When an mP mass strikes the west coast of North Americait releases its moisture in the form of showers and, in northern regions, snow.
The term front was suggested by the Bjerkneses because the collisions of two air masses reminded them of a battlefront during a military operation. That collision often results in warlike weather phenomena between the two air masses. Fronts develop when two air masses with different temperatures and, usually, different moisture content come into contact with each other. When that happens, the two bodies of air act almost as if they are made of two different materials, such as oil and water.
Imagine what happens, for example, when oil is dribbled into a glass of water. The oil seems to push the water out of its way and, in return, the water pushes back on the oil. A similar shoving match takes place between warm and cold air masses along a front. The exact nature of that shoving match depends on the relative temperature and moisture content of the two air masses and the relative movement of the two masses.
One possible situation is that in which a mass of cold air moving across the earth's surface comes into contact with a warm air mass. When that happens, the cold air mass may force its way under the warm air mass like a snow shovel wedging its way under a pile of snow. The cold air moves under the warm air because the former is denser.
The boundary formed between these two air masses is a cold front. Cold fronts are usually accompanied by a falling barometer and the development of large cumulonimbus clouds that bring rain showers and thunderstorms. During the warmer seasonsthe clouds form as moisture-rich air inside the warm air mass, which is cooled as it rises; water subsequently condenses out as precipitation.
The two designations are c for continental land air mass and m for maritime water air mass. A second letter, written in upper case, indicates the approximate latitude and, therefore, temperature of the region: A for arctic; P for polar; E for equatorial; T for tropical.
The two letters are then combined to designate both humidity and temperature of an air mass.
High School Earth Science/Changing Weather
An air mass that developed in a source region over a large body of tropical water would be labeled mT water, warm. An air mass that developed in a source region over an arctic land-mass would be labeled cA land, cold. Fronts Air masses create weather as they are moved by winds around the globe. Fronts develop at the boundary where two air masses with different temperatures—and, usually, different humidities—come into contact with each other.
Air masses and fronts
The term front was suggested by the Bjerkneses because the collision of two air masses reminded them of a battlefront during a military operation. Words to Know Continental: Referring to very large land masses.
The amount of moisture in the air. Referring to the oceans. Referring to the surface features of an area. A cold front develops when a cold air mass moves into an area occupied by a warm air mass. Because cold air is heavier or more dense than warm air, the cold air mass moves under the warm air mass. Cold fronts are usually accompanied by a decrease in air pressure and the development of large cumulus and cumulonimbus clouds that bring rain showers and thunderstorms.
Fronts ( Read ) | Earth Science | CK Foundation
Rainfall and winds are most severe along the boundary between the two air masses. Cold fronts are represented on weather maps by solid lines with solid triangles. The direction in which the triangles point shows the direction in which the cold front is moving. A warm front develops when a warm air mass approaches and then slides up and over a cold air mass.
As the warm air mass comes into contact with the cold air mass, it is cooled and some of the moisture held within it condenses to form clouds.
In most cases, the first clouds to appear are high cirrus clouds.