Mid-latitude cyclone

Whatis a mid-latitude cyclone?

-Themid-latitude cyclone is a synoptic scale low pressure device that has actually cyclonic(counter-clockwise in northern hemisphere) circulation that is found in the middlelatitudes (i.e., 30�N-55�N)


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

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

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

Here is a snapshot of a common mid-latitudecyclone and hurricane. Notice the size difference.

You are watching: A trough aloft is generally associated with:


How does the mid-latitudecyclone kind (for a longer description read pages 219-228)

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

2.Alongthis border a counter-clockwise circulation can collection up at the surface, whichacts to take warm air increase from the south and cold air under from the north. Thisis called cyclogenesis.

3.Inthe facility of this circulation, there is fixed convergence (all the waiting ismoving in towards the facility of the circulation lot like when you make a whirl-poolin a pool, all the leaves and stuff floating about moves towards the center).When all the air hits the center, we have actually rising motion since it has actually nowhereelse come go.

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

a.Ifthe upper levels aren�t favorable for cyclone development, the cyclone won�tgrow and the mass convergence right into the short at the surface ar will just pile increase andfill in the Low and it will decay.

b.Referto the 2nd figure below for the optimal situation.

5.Ifthe top levels room favorable, climate the mid-latitude cyclone will proceed todevelop and also bring increase mT air in the warmth sector and bring down cP waiting in thecold sector.

a.ThemT wait rises together it moves out ahead that the short helping to deepen the Lowpressure center to the eastern and assist it move along

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

i.Itis this transport of energy 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 will maturity, the central pressure will be at itslowest and also the occluded former will begin to type (as the cold front catches upto the warm front).

8.Oncethe system is occluded (all the warmth air is over the cold air) the fixed convergenceacts to fill in the Low and therefore the pressure increases in the Low and thesystem decays.

See more: What Does Twice A Day Mean Every 12 Hours? Does Twice A Day Mean Every 12 Hours

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



Theabove figures were taken native www.u.arizona.edu/~korine/230/chap10_figs.htm


Diagram of circulation (circulation) transparent thedepth the the troposphere


Wheredo mid-latitude cyclones typically form (in north America in winter)? (Remember the cycloneslike to build along waiting mass boundaries)

-Leeside the the Rockies = Lee Cyclones

o Alberta Clippers

�FASTMOVING and also usually don�t have actually too much precip associated with them because theyare much from a humidity source


�IntenseLow, with solid warm waiting advection in the warmth sector, very cold temps in thecold sector. If over there is a many gulf humidity to work-related with, they over there isusually sleet, freezing rain and rain connected with the heat front, solid thunderstormsalong the southerly edge the the cold front and snow along the backside and also tothe NW the the short (even BLIZZARDS)

-Alongthe east Coast

o Gulf Low

�Formalong the southern coast where over there is a heat boundary between the warmocean and also cool land. Usually have actually a lot of precip linked with them because theyare for this reason close come the ocean

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

�Theseare the most INTENSE systems and they form along the thermal border betweenthe warmth Gulf Stream and the cold Atlantic coast. Lock can lug flooding rainsalong the coast and several feet that snow further inland together they usage the oceanas a vast source of the moisture. These likewise develop very quickly and sometimeshave pressure drops of 24mb in a single day. V a pressure drop the thismagnitude you deserve to imagine how rapid the winds are about these things.

What are their usual tracks? view diagrambelow


Precip patterns (and types),winds, temperatures, fronts, top level flow and clouds that are approximately a typicalmid-latitude cyclone in winter.