Anemometer beam exits reflect, or backscatter, the light back into a detector, where it is measured relative to the original laser beam. When the particles are in great motion, they produce a Doppler shift for measuring wind speed in the laser light, which is used to calculate the speed of the particles, and therefore the air around the anemometer. Ultrasonic anemometers, first developed in the 1950s, use ultrasonic sound waves to measure wind velocity. They measure wind speed based on the time of flight of sonic pulses between pairs of transducers. Measurements from pairs of transducers can be combined to yield
Does Anybody Really Know What Time It Is? Does Anybody Really Know What Time It Is? "Does Anybody Really Know What Time It Is?" is a song by the rock band Chicago. It was included on their 1969 debut album "Chicago Transit Authority" and released as a single in 1970. The song was written and sung by Robert Lamm. The song was not released as a single until two tracks from the band's second album, "Make Me Smile" and "25 or 6 to 4", had become hits. It became the band's third straight Top 10 single, peaking at in the U.S. and No. 2 in Canada. Because the