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
What Kate Does reviews"; however, this was down significantly from the previous episode's 89 and Bonnie Covel of About.com noted that " 'What Kate Does' brought us a bit of negativity. In general, fans just didn't like the episode". "What Kate Does" was largely considered to be a step down from the season premiere in pacing, revelations and writing; Mike Hale of "The New York Times" described the episode as "contemplative", "anticlimactic" and "subdued" and the flash sideways as "kind of boring and seemingly pointless." Chris Carabott of IGN, who gave the episode a score of 7.3 summed up that " 'What Kate