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For example, a dataset that measures wind speeds of 1° and 359° would average to 180°, but expressing the same data as 1° and -1° (equal to 359°) would give an average of 0°. Thus, we define circular moments by placing all measured angles on a unit circle, then calculating the moments of these points.
A polar diagram, or polar plot, is a graph that shows a sailboat's potential speed over a range of wind speeds and relative wind angles. [1] It normally consists of the right side of a line chart with the radius representing the yacht speed and the angle representing the wind direction blowing from top to bottom. Several lines are normally ...
The eddy covariance (also known as eddy correlation and eddy flux) is a key atmospheric measurement technique to measure and calculate vertical turbulent fluxes within atmospheric boundary layers. The method analyses high-frequency wind and scalar atmospheric data series, gas, energy, and momentum, [ 1 ] which yields values of fluxes of these ...
The apparent wind on board (a boat) is often quoted as a speed measured by a masthead transducer containing an anemometer and wind vane that measures wind speed in knots and wind direction in degrees relative to the heading of the boat. Modern instrumentation can calculate the true wind velocity when the apparent wind and boat speed and ...
Wind direction is generally reported by the direction from which the wind originates. For example, a north or northerly wind blows from the north to the south; [1] the exceptions are onshore winds (blowing onto the shore from the water) and offshore winds (blowing off the shore to the water). Wind direction is usually reported in cardinal (or ...
The mathematical formulas that equate to the results of the flight computer wind calculator are as follows: (desired course is d, ground speed is V g, heading is a, true airspeed is V a, wind direction is w, wind speed is V w. d, a and w are angles. V g, V a and V w are consistent units of speed. is approximated as 355/113 or 22/7)
Roughness length is a parameter of some vertical wind profile equations that model the horizontal mean wind speed near the ground. In the log wind profile, it is equivalent to the height at which the wind speed theoretically becomes zero in the absence of wind-slowing obstacles and under neutral conditions. In reality, the wind at this height ...
If the wind direction is constant, the longer the fetch and the greater the wind speed, the more wind energy is transferred to the water surface and the larger the resulting sea state will be. [4] Sea state will increase over time until local energy dissipation balances energy transfer to the water from the wind and a fully developed sea results.