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Meteorology
3.4.2 Atmospheric movement
The illustration here can give an
impression of the global wind
system.
The red arrows represent warm
air masses, while the blue
arrows represent cold air
masses.
It also gives an impression of
how the warm air cools with
altitude, while the cold air
warms as it moves toward the Earth.
3.4.2.1 Pressure Gradient Force
The pressure gradient describes the change in air pressure over a given
distance. If the air pressure is low in one area and high in another, a pressure
gradient will occur, creating a force that pulls air from high-pressure areas to
low-pressure areas.
This pressure gradient force is primarily responsible for air movement and wind
creation. The greater the pressure difference (i.e., the steeper the pressure
gradient), the stronger the wind will be.
The pressure difference between systems determines the strength of the
gradient force. When isobars are close together, the pressure gradient is large,
resulting in strong winds.
Isobar Distance in hPa
Pressure Gradient Force =
Isobar Distance in km
Flight Theory PPL(A)(UL)/LAPL Henning Andersen, Midtjysk Flyveskole© 2025 248
