Wind speed 3 May 1999 is often quoted as the highest-recorded surface wind speed, although another figure of has also been quoted for the same tornado. Yet another number used by the Center for Severe Weather Research for that measurement is . However, speeds measured by Doppler radar are not considered official records. An anemometer is one of the tools used to measure wind speed. A device consisting of a vertical pillar and three or four concave cups, the anemometer captures the horizontal movement of air particles (wind speed). Another tool used to measure wind velocity includes a GPS combined with pitot
Radon measure regular, and locally finite, and inner regular for open sets. It coincides with "m" on compact and open sets, and "m" can be reconstructed from "M" as the unique inner regular measure that is the same as "M" on compact sets. The measure "m" is called moderated if "M" is σ-finite; in this case the measures "m" and "M" are the same. (If "m" is σ-finite this does not imply that "M" is σ-finite, so being moderated is stronger than being σ-finite.) On a strongly Lindelöf space every Radon measure is moderated. An example of a measure "m" that is