Definition of the Day
Atmospheric Instability
A condition in the atmosphere where air parcels are heated and therefore are warmer than the surrounding atmosphere resulting in unstable weather conditions such as heavy rains and hailstorms. See Atmospheric Stability & Instability

Pressure Gradient,Coriolis force and Geostrophic winds

Wind is the horizontal movement of air resulting in pressure differences on the earth's surface.Winds move from high to low pressure areas.Factors affecting winds are:

Pressure gradient force

PGF is the initial driving force of wind.Closely spaced isobars results in a steep(high) PGF thus high wind speeds while a weak PGF is caused by widely spaced isobars.(Isobars are lines connecting areas of equal pressure.)
pressure gradient force
img by GEODeEarthScience

Coriolis Force

Insted of wind moving in a straight path,it is deflected in its direction of flow by the Coriolis Force.The Coriolis Force is a result of earth's rotation and redirects wind to the left in the Southern Hemisphere and to the right in the Northern Hemisphere.The Coriolis force is affected by high wind speeds,the higher the wind speed the more air will be deflected in its line of path. The Coriolis force act at right angles to thr direction of air flow.
Coriolis Effect
Coriolis Force

Geostrophic Wind

This is when wind flows parallel to the isobars caused by a balance between the Coriolis force and the PGF.A geostrophic wind occurs at higher elevations where friction is less.
Geostrophic Wind
Friction at lower layers(surface) affects wind speeds thus the Coriolis Force.

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1 Comment

2018-06-03 23:05:41
good for revision