Anemometer use is constructed from a ping-pong ball attached to a string. When the wind blows horizontally, it presses on and moves the ball; because ping-pong balls are very lightweight, they move easily in light winds. Measuring the angle between the string-ball apparatus and the vertical gives an estimate of the wind speed. This type of anemometer is mostly used for middle-school level instruction, which most students make on their own, but a similar device was also flown on Phoenix Mars Lander. The first designs of anemometers that measure the pressure were divided into plate and tube classes. These are the
Carleson measure then the measure "μ" is said to satisfy the vanishing Carleson condition if "C"("R") → 0 as "R" → 0. Carleson measure In mathematics, a Carleson measure is a type of measure on subsets of "n"-dimensional Euclidean space R. Roughly speaking, a Carleson measure on a domain Ω is a measure that does not vanish at the boundary of Ω when compared to the surface measure on the boundary of Ω. Carleson measures have many applications in harmonic analysis and the theory of partial differential equations, for instance in the solution of Dirichlet problems with "rough" boundary. The Carleson condition