Spindrift states: Force 8, defined as "Gale". Wind speed 39-46 mph, equal to 34-40 knots. Inland, twigs break off trees; progress generally impeded. At sea, moderately high waves of greater length; edges of crests begin to break into spindrift; foam is blown in well-marked streaks along the direction of the wind. Relatedly, "spindrift" can also be used to describe fine sand or snow that is blown off by the wind. "Spindrift" is a southern English word, "Spoondrift" a northern or Scottish word. The Scottish word "spoondrift" can be used to describe fine snow that is blown off the hills by the
Geostrophic wind depends on the local Rossby number. It is invalid at the equator, because "f" is equal to zero there, and therefore generally not used in the tropics. Other variants of the equation are possible; for example, the geostrophic wind vector can be expressed in terms of the gradient of the geopotential Φ on a surface of constant pressure: Geostrophic wind The geostrophic wind () is the theoretical wind that would result from an exact balance between the Coriolis force and the pressure gradient force. This condition is called geostrophic balance. The geostrophic wind is directed parallel to isobars (lines of