Physics and Surfing :: physics surf surfing

When a wind begins to ravage across a flat body of wet ripples form intimately immediately, then wavelets, and finally nearly fully developed waves, having almost defined wave lengths and shapes. Surface waves give also form, during calm wind, where opposing currents meet. This is cognise as current rips and disregard be dangerous for small or oerloaded boats. A good estimate of the wind zip up can be obtained by observing its effect on the water. For example, at 5 sweeps only small wavelets can be observed. A 10 knot wind speed will produce a few ashencaps. At 15 knots whitecaps can be seen up to 30% of the area. At 20 knots whitecaps can be seen upto 60% of the area. At 30 knots whitecaps and sprinkle can be seen all over and foam from the breakers begins to form. At 40 knots streaks of foam can easily be seen. At 50 knots visibility is reduced and the sea begins to take on a white appearance from all the foam. Current directions and speed will greatly contact the area s covered by spray and breakers. Factors Affecting Wave Heights1. run up.2. Wind duration.3. Length and width of wind fetch. (This is the distance over the water in which the wind blows in nearly the same direction.)4. Depth of the water.5. Direction and speed of the current.6. Rate of precipitation.7. Air temperature.8. Amounts of flotsam, ice, or seaweed in the fetch area. 1. How high will the waves convey? Maximum wave tips (in feet) will not get any higher than * the wind speed in knots. This is correct over 90% of the time. Note Wave height begins to increase when the depth of the water is less than or equal to 1/4 of the wavelength because the wave starts to achieve the sea floor. 2. What is the difference between waves and swells? Waves occur where the wind is blowing. Swells are waves that lay down moved away from the wind generating area and frequently give warnings of an approach shot storm. 3. What is the significant wave height? Significant wave height (SWH) is the second-rate height of 1/3 of the highest waves, or the height of the waves an observer is most likely to report. The significant wave height is used in the marine forecasts. Table 1.Wave heights in relationship to the significant wave height (SWH)Most frequent wave height .5 x SWH