Chapter_08_Part1_Atmospheric_Pressure Flashcards
What is atmospheric pressure?
Force exerted by air over a unit area.
How does air pressure change with altitude?
It decreases exponentially with increasing altitude.
What is a barometer?
An instrument measuring atmospheric pressure.
Differentiate station pressure and sea-level pressure.
Station pressure is the actual barometer reading at location/elevation; sea-level pressure is adjusted to mean sea level.
Define Pressure Gradient Force (PGF).
Force causing air to move from high to low pressure due to pressure differences.
What causes horizontal pressure variations?
Differences in temperature and density across air columns.
How do mercury barometers work?
Air pressure forces mercury upward in a tube; height of mercury indicates pressure.
What is an aneroid barometer?
A barometer using a flexible metal box (aneroid cell) to measure air pressure changes.
Why use mercury in barometers?
Mercury is dense and doesn’t evaporate like water.
What does high surface pressure indicate about air temperature at the surface?
Typically indicates colder air at the surface.
