|WHY DOES THE PGF POINT|
FROM HIGH TO LOW PRESSURE?
METEOROLOGIST JEFF HABY
In nature, equilibrium and balance are goals. When nature is in balance, stability is attained. When nature is
out of balance, it does everything within the natural laws to regain that balance. Perhaps everything that happens
in nature has a purpose and a cause. This balance is not attained instantaneously. It takes the dimension of time
to correct any action that causes an imbalance. When a region of excess is placed next to a region of deficit,
nature tries to equalize the regions.
Place cold water into warm water, and the waters will mix and with time will
come into an equilibrium temperature between that of the original cold and warm waters. Heat ALWAYS travels from
warm objects toward cold objects. Why? Warm represents an excess while cold represents a deficit of heat. Heat
travels from the region of excess to deficit. In the atmosphere, there are regions with an excess
those with a deficit pressure. Regions with an excess pressure are termed high pressure and those with a deficit,
low pressure. To equalize the pressure, nature moves the air from the high pressure toward that of the deficit
low pressure. It is like a car tire. The air pressure inside a car tire is greater than that outside the car tire.
When the tire has a leak, the air travels from inside the tire to outside the tire OR from a region of excess
pressure to a region of deficit pressure. This is the reason the pressure gradient force is directed from high
to low pressure.