## Section5.4Other forces

The centrifugal force is caused by centripetal acceleration (toward the center of the rotation); for wind the centrifugal force points outward from the center of rotation (that is, it is the tendency of wind to want to travel in a straight line)

\begin{equation*} CENT=\frac{V^2}{R} \end{equation*}

where $$R$$ is positive for cyclonic flow and negative for anticyclonic flow: works against PGF around lows and with PGF around highs; this force also gets very strong for small turning radii.

Friction with the surface will decelerate the wind; this force thus always moves in the direction opposite the wind. It is described by

\begin{equation*} FF=-kV \end{equation*}

where $$V$$ is the wind speed and $$k$$ describes the roughness of the surface. Trees and tall buildings have much more "roughness" whereas sand/snow/water have very low roughness.