BUYS BALLOT’S LAW

If an observer in the Northern Hemisphere faces the surface wind, the center of low pressure is toward his right, somewhat behind him; and the center of high pressure is toward his left and somewhat in front of him.

If an observer in the Southern Hemisphere faces the surface wind, the center of low pressure is toward his left, somewhat behind him; and the center of high pressure is toward his right and somewhat in front of him.

Buys Ballot’s Law: OriginThe law was first deduced by American

meteorologists J.H Coffin and William Ferrel. This was then known as the Ferrel’s law.

On November 1857, Christophorus Henricus Diedericus Buys Ballot(October 10, 1817 – February 3, 1890) published Comptes Rendus containing emperical validation of Ferrel’s initial theory in 1856 now known as the Buys Ballot’s Law.

C.H.D Buys BallotWilliam Ferrel

The Buys Ballot’s Law first appeared in early version of Nathaniel Bowditch’s American Practical Navigator (1900) and other publications to assist in passage planning and safe conduct of ships at sea.

Nathaniel Bowditch(March 26, 1773 – march 16, 1838)

Application of Buys Ballot’s LawThe general purpose of the law is to

assist steering a vessel away from the center and the right, in the Northern Hemisphere, or left, in the Southern Hemisphere, quadrants of hurricanes or any other rotating disturbance at sea.

Other use is to help establish the probability of the existence of a storm and the best course to steer to avoid the worst of it.

Observed in purpose of the law The following are observed in establishing

weather predictions to be conformed with the law:

1. visible cloud formation2. wind direction and speed (wind vane

and anemometer)3. atmospheric pressure (barometer)4. other systems

Buys Ballot on Storm formationHow do storms form?

The factors that contributes to the formation of the storm includes:

1. water temperature(atleast 26.5 °C or 79.7 °F with the depth of atleast 50m or 160ft.)

2. rapid cooling with height(allowing the release of heat of condensation empowering the cyclone)

3. high humidity4. low amounts of wind-shear.5. must be atleast 555km(345mi) or 5 degrees away

from the equator(to allow coriolis effect and deflect winds blowing towards the low pressure)

6. a pre-existing weather disturbance.

Location of a stormThe location of most storm formation is

in between 10 and 30 degrees away from the equator. Because Coriolis effect initiates and maintains cyclone rotation, cyclones, rarely forms within 5 degrees of the equator.

Strength of the stormHurricanes intensify when moving over areas of

increased water temperatures, and weaken over colder water surfaces. Upper atmosphere wind shear (different wind direction and speeds at different elevations) will frequently prevent or slow intensification of tropical storms by "spreading out" the storm horizontally and preventing the formation of strong updrafts of warm, humid air. Movement over a land-mass will weaken hurricane winds but will result in large-scale rain that can result in large-scale flooding. When encountering a strong frontal system (such as a polar front) the hurricane will curve and track along the leading edge of the front or become implanted in it.