Coldfront - Development of Cold Front

Development of Cold Front

The cooler and denser air wedges under the less-dense warmer air, lifting it. This upward motion causes lowered pressure along the cold front and can cause the formation of a narrow line of showers and thunderstorms when enough moisture is present. On weather maps, the surface position of the cold front is marked with the symbol of a blue line of triangles/spikes (pips) pointing in the direction of travel. A cold front's location is at the leading edge of the temperature drop off, which in an isotherm analysis would show up as the leading edge of the isotherm gradient, and it normally lies within a sharp surface trough. Cold fronts move faster than warm fronts and can produce sharper changes in weather. Since cold air is denser than warm air, it rapidly replaces the warm air preceding the boundary.

In the northern hemisphere, a cold front usually causes a shift of wind from southwest to northwest clockwise, also known as veering, and in the southern hemisphere a shift from northeast to southwest, in a clockwise manner. Normally, cold fronts can be marked by these characteristics:

Weather phenomenon Prior to the Passing of the Front While the Front is Passing After the Passing of the Front
Temperature Warm Cooling suddenly Steadily cooling
Atmospheric pressure Decreasing steadily Lowest, then sudden increase Increasing steadily
Winds Gusty; shifting
  • North to west, usually northwest (northern hemisphere)
  • South to west, usually southwest (southern hemisphere)
Precipitation/conditions* Light patchy rain can be produced by stratocumulus or stratus in the warm sector. In summer, sometimes thunderstorms if a preceeding squall line is present. Prolonged rain (nimbostratus) or thunderstorms (cumulonimbus): depends on conditions. Showers, then clearing
Clouds* Often preceded by cirrus, cirrostratus then altostratus like a warm front (but usually with smaller amounts of these clouds). Areas of cirrocumulus and altocumulus within cirrostratus and altostratus more commonly seen than at a warm front. Larger cumulus clouds under the higher cloud types than at a warm front, where stratocumulus and cumulus humilis usually occur. Some of these cumulus clouds may produce showers ahead of the front. Cumulonimbus and cumulus congestus producing frequent showers, with a sheet of upper altostratus, through which the sun can sometimes be seen. Less commonly nimbostratus occurs with continuous rain. Patchy altocumulus or stratocumulus and higher cirrus clouds along with fast moving stratus fractus then eventually scattered cumulus and sometimes cumulonimbus.
Visibility* Fair to poor in haze Poor, but improving Good, except in showers
Dew Point High; steady Sudden drop Falling

*Provided there is sufficient moisture.

Read more about this topic:  Coldfront

Famous quotes containing the words development of, front, development and/or cold:

    Fascism, the more it considers and observes the future and the development of humanity, quite apart from political considerations of the moment, believes neither in the possibility nor the utility of perpetual peace.
    Benito Mussolini (1883–1945)

    That big gun in your hand makes you look grown up—you think! I’ll bet you spend hours posing in front of a mirror holding it, trying to look tough!... You scum!
    Richard Brooks (1912–1992)

    They [women] can use their abilities to support each other, even as they develop more effective and appropriate ways of dealing with power.... Women do not need to diminish other women ... [they] need the power to advance their own development, but they do not “need” the power to limit the development of others.
    Jean Baker Miller (20th century)

    April is in my mistress’ face,
    And July in her eyes hath place,
    Within her bosom is September,
    But in her heart a cold December.
    —Unknown. Subject #4: July Subject #5: September Subject #6: December. All Seasons in One. . .

    Oxford Book of Sixteenth Century Verse, The. E. K. Chambers, comp. (1932)