EESA09H3 Lecture : Lecture8_notes.pdf
Document Summary
Outline of this lecture: part i measuring wind. Wind rose: sound of wind, part ii wind strength scales, beaufort, fujita, saffir-simpson, part iii special focus: mach speeds and sonic booms. Anemometers are instruments used to measure wind speed. Weather vanes or wind vanes are used to measure wind direction. There are at least seven types of anemometers. These anemometers are primarily used to measure wind at or near the surface of the earth. Higher level winds are measured using radiosonde (weather balloons) or deduced from pressure distribution. Upper level winds are geostrophic and thus the knowledge or the pressure gradient enables us to calculate the wind speed and direction: deflection. The first anemometer was invented by leon battista alberti in italy in 1450. He linked wind speed to the deflection of a horizontal plate. He hooked the plate to a spring and measured the compression of the spring. Leonardo da vinci created a similar anemometer a few decades later.