Air Masses

Polar (P) Air Mass

. Continental Polar Air Masses cold temperatures and little moisture. Those who live in northern portions of the United States expect cold weather during the winter months. These conditions usually result from the invasion of cold arctic air masses that originate from the snow covered regions of northern Canada.

Stationary Front

A stationary front is a pair of air masses, neither of which is strong enough to replace the other. On a weather map, this is shown by an inter-playing series of blue spikes pointing one direction and red domes pointing the other.

Tornado Warning

A tornado warning means that a tornado is imminent: A tornado is occurring or is expected to develop. Tornado warnings are issued by the local National Weather Service office when any of the following occurs: Doppler radar indicates strong rotation within a thunderstorm

Tropical Depression

A tropical depression forms when a low pressure area is accompanied by thunderstorms that produce a circular wind flow with maximum sustained winds below 39 mph. Most tropical depressions have maximum sustained winds between 25 and 35 mph

Tornado Watch

A watch does not mean that the severe weather is actually occurring, only that atmospheric conditions have created a significant risk for it. If severe weather actually does occur, a tornado warning or severe thunderstorm warning would then be issued.

Arctic (A) Air Mass

Colder air masses are termed polar or arctic, while warmer air masses are deemed tropical. Continental and superior air masses are dry while maritime and monsoon air masses are moist. Weather fronts separate air masses with different density (temperature and/or moisture) characteristics.

Maritime (m) Air Mass

Colder air masses are termed polar or arctic, while warmer air masses are deemed tropical. Continental and superior air masses are dry while maritime and monsoon air masses are moist. Weather fronts separate air masses with different density (temperature and/or moisture) characteristics.

Air-mass Weather

In meteorology, an air mass is a volume of air defined by its temperature and water vapor content. Air masses cover many hundreds or thousands of square miles, and adapt to the characteristics of the surface below them. They are classified according to latitude and their continental or maritime source regions.

Mid-latitude Cyclone

These types of cyclones are defined as synoptic scale low pressure weather systems that occur in the middle latitudes of the Earth (outside the tropics) not having tropical characteristics, and are connected with fronts and horizontal gradients in temperature and dew point otherwise known as "baroclinic zones".

Air Mass

a body of air with horizontally uniform temperature, humidity, and pressure.

Occluded Front

a composite front produced by occlusion.

Tropical Storm

a localized, very intense low-pressure wind system, forming over tropical oceans and with winds of hurricane force.

Tornadoes

a mobile, destructive vortex of violently rotating winds having the appearance of a funnel-shaped cloud and advancing beneath a large storm system.

Occlusion

a process in which the cold front of a rotating low-pressure system overtakes the warm front, forcing the warm air upward above a wedge of cold air.

Doppler Radar

a radar tracking system using the Doppler effect to determine the location and velocity of a storm, clouds, precipitation, etc.

Storm Surge

a rising of the sea as a result of atmospheric pressure changes and wind associated with a storm.

Hurricane

a storm with a violent wind, in particular a tropical cyclone in the Caribbean.

Thunderstorm

a storm with thunder and lightning and typically also heavy rain or hail.

Continental (c) Air Mass

air mass that develops over northern Canada is called a continental polar air mass and is cold and dry. One that forms over the Indian Ocean is called a maritime tropical air mass and is warm and humid

Source Region

an extensive region of the earth's surface where large masses of air having uniform temperature and humidity conditions characteristic of the region originate.

Fronts

front in Science Expand. front. (frŭnt) The boundary between two air masses that have different temperatures or humidity. In the mid-latitude areas of the Earth, where warm tropical air meets cooler polar air, the systems of fronts define the weather and often cause precipitation to form.

Lake-effect Snow

snow falling on the lee side of a lake, generated by cold dry air passing over warmer water, especially in the Great Lakes region.

Overrunning

spread over or occupy (a place) in large numbers.

Eye Wall

the area immediately outside the eye of a hurricane or cyclone, associated with tall clouds, heavy rainfall, and high winds.

Cold Front

the boundary of an advancing mass of cold air, in particular the trailing edge of the warm sector of a low-pressure system.

Warm Front

the boundary of an advancing mass of warm air, in particular the leading edge of the warm sector of a low-pressure system.

Tropical (T) Air Mass

tropical continental. The definition of a tropical continental is a dry air mass formed over land in area close to the equator. An example of a tropical continental is a mass of warm air that forms over northern Mexico.