Midlatitude Cyclonic Systems Flashcards
What is a Midlatitude cyclone (wave cyclone)
An organized area of low pressure, with converging and ascending airflow producing an interaction of air masses; migrates along storm tracks. Such lows, or depressions, form the dominant weather pattern in the middle and higher latitudes of both hemispheres.
Where is a midlatitude or extratropical cyclone born (Originates)
A mid-latitude cyclone, or an extratropical cyclone, is born along the polar front, particularly in the region of the Icelandic and Aleutian subpolar low-pressure cells in the Northern Hemisphere.
What is a storm track?
Seasonally shifting path followed by a migrating low-pressure system
On average, how long dose it take for a midlatitude cyclone system to progress through its life cycle?
On average, a midlatitude cyclonic system takes 3–10 days to progress through this life cycle from the area where it develops to the area where it finally dissolves.
What is the first stage of a midlatitude cyclone?
Cyclogenesis
An atmospheric process that describes the birth of a midlatitude wave cyclone, usually along the polar front. Also refers to strengthening and development of a midlatitude cyclone along the eastern slope of the Rockies, other north–south mountain barriers, and the North American and Asian east coasts.
“A disturbance develops along the polar front or in certain other areas. Warm
air converges near the surface and begins to rise, creating instability. “
What is the second stage of a midlatitude cyclone?
Open Stage
“Cyclonic, counterclockwise flow pulls warm, moist air from the south into the low-pressure center while cold air advances southward west of the center”
In the open stage, to the east of the developing low-pressure centre of a Northern Hemisphere midlatitude cyclone, warm air begins to move northward along an advancing front, while cold air advances southward to the west of the centre. See this organization in Figure GIA 8.1, Stage 2, and around the centre of low pressure, located over Winnipeg, in the GIA map. As the midlatitude cyclone matures, the counterclockwise flow draws the cold air mass from the north and west and the warm air mass from the south. In the cross section, you can see the profiles of both a cold front and a warm front and each air mass segment.
What is an Occluded front?
Occluded front (8) In a cyclonic circulation, the overrunning of a surface warm front by a cold front and the subsequent lifting of the warm air wedge off the ground; initial precipitation is moderate to heavy.
What is the third state of a midlatitude cyclone
“The faster-moving cold front overtakes the slower warm front and wedges beneath it. This forms an occluded front, along which cold air pushes warm air upward, causing precipitation”
Next is the occluded stage. The colder cP air mass is denser than the warmer mT air mass. This cooler, more unified air mass, acting like a bulldozer blade, moves faster than the warm front. Cold fronts can travel at an average 40 km · h−1, whereas warm fronts average roughly half that, 16–24 km · h−1. Thus, a cold front often overtakes the cyclonic warm front and wedges beneath it, producing an occluded front (occlude means “to close”).
What is the final stage of a midlatitude cyclone?
Dissolving stage: The midlatitude cyclone dissolves when the cold air mass completely cuts off the warm air mass from its source of energy and moisture.
