Mid-latitude cyclone

Whatis a mid-latitude cyclone?

-Themid-latitude cyclone is a synoptic scale low pressure system that has actually cyclonic(counter-clockwise in north hemisphere) flow that is discovered in the middlelatitudes (i.e., 30�N-55�N)


o over there is a place (tropics vs.mid-latitudes) and also size difference between hurricane and also mid-latitude cyclone

�Typicalsize the mid-latitude cyclone = 1500-5000km in diameter

�Typicalsize the a hurricane or tropic storm = 200-1000km in diameter

Here is a snapshot of a typical mid-latitudecyclone and hurricane. An alert the dimension difference.

You are watching: How does surface air flow in a middle-latitude cyclone in the northern hemisphere


How walk the mid-latitudecyclone type (for a longer description read pages 219-228)

1.Frompolar prior theory, we understand that in the mid-latitudes there is a boundary betweencold dry (cP) air to the north and also warm moist (mT) air to the south

2.Alongthis boundary a counter-clockwise circulation can set up in ~ the surface, whichacts to take warmth air increase from the south and also cold air down from the north. Thisis dubbed cyclogenesis.

3.Inthe center of this circulation, there is fixed convergence (all the air ismoving in towards the facility of the circulation much like once you make a whirl-poolin a pool, all the leaves and also stuff floating approximately moves towards the center).When all that air access time the center, we have rising motion because it has actually nowhereelse come go.

4.Ifthe upper levels are favorable because that cyclone development, then there is a regionof aberration aloft over the arising Low-pressure center. This will helppull the air that is converging at the surface upward and continue to build thesurface cyclone. (The top levels also steer the system and make it progresseast (like us learned earlier)).

a.Ifthe top levels aren�t favorable because that cyclone development, the cyclone won�tgrow and the massive convergence right into the short at the surface ar will just pile up andfill in the Low and it will decay.

b.Referto the second figure below for the optimal situation.

5.Ifthe top levels are favorable, then the mid-latitude cyclone will proceed todevelop and bring up mT air in the heat sector and bring under cP air in thecold sector.

a.ThemT waiting rises as it moves out ahead the the low helping come deepen the Lowpressure center to the eastern and help it move along

b.ThecP air sink behind the system and also fills in the low on the backside alsohelping to relocate the device along

i.Itis this transfer of power that both strengthens and also propagates themid-latitude cyclone!

6.Oncethe mid-latitude cyclone is totally developed, well-defined fronts appear.

7.Asthe mid-latitude cyclone get maturity, the main pressure will be at itslowest and also the occluded prior will start to type (as the cold front records upto the warmth front).

8.Oncethe device is occluded (all the heat air is above the cold air) the fixed convergenceacts to fill in the Low and also therefore the pressure increases in the Low and thesystem decays.

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Evolution the a mid-latitude cyclone. Each figurefollows the description over 1-8



Theabove numbers were taken from www.u.arizona.edu/~korine/230/chap10_figs.htm


Diagram of flow (circulation) throughout thedepth of the troposphere


Wheredo mid-latitude cyclones typically kind (in phibìc America in winter)? (Remember that cycloneslike to develop along waiting mass boundaries)

-Leeside that the Rockies = Lee Cyclones

o Alberta Clippers

�FASTMOVING and also usually don�t have too lot precip linked with them since theyare much from a moisture source


�IntenseLow, with strong warm wait advection in the warmth sector, an extremely cold temps in thecold sector. If there is a most gulf humidity to work with, they over there isusually sleet, freezing rain and rain connected with the warm front, solid thunderstormsalong the southerly edge that the cold front and also snow along the backside and tothe NW of the short (even BLIZZARDS)

-Alongthe eastern Coast

o Gulf Low

�Formalong the southern shore where there is a thermal boundary in between the warmocean and also cool land. Usually have actually a many precip linked with them due to the fact that theyare therefore close come the ocean

oHatterasLow and also Nor�easters (aka ��bomb�cyclones)

�Theseare the most INTENSE systems and they kind along the thermal boundary betweenthe heat Gulf Stream and also the cold Atlantic coast. Castle can lug flooding rainsalong the coast and also several feet the snow more inland as they use the oceanas a vast resource of the moisture. These likewise develop really quickly and sometimeshave pressure drops the 24mb in a solitary day. V a pressure drop that thismagnitude you deserve to imagine how fast the winds are about these things.

What room their typical tracks? see diagrambelow


Precip fads (and types),winds, temperatures, fronts, upper level flow and clouds that are around a typicalmid-latitude cyclone in winter.