What are the two ways in which a wind vane measures the wind speed?

Answer 1

There are three common types of anemometers:

• Cup Anemometer

This is the most commonly used type of anemometer. It consists of several metal cups (usually three) which are attached to the ends of horizontal arms, which are mounted on a vertical shaft. When wind gets caught in the cups, it moves. This turns the shaft which is connected to an electrical generator which gives the wind speed (the amount of electricity produced depends on the wind speed) in miles per hour, kilometers per hour, or knots.

• Propeller Anemometer

Here, the wind turns a propeller instead of cups. It is used where the direction of wind changes, and is usually connected to a weather vane. The vane shows the correct wind direction, and the propeller indicates the wind speed. This type of anemometer is usually used to measure air flow in ventilating shafts.

• Hot-wire anemometer

It consists of an electrically heated wire exposed to the wind. The rate of heat loss from the wire depends on the wind speed. The wind speed is determined by measuring the electricity required to maintain the wire at a constant temperature. This type of anemometer is mainly used in experimental work.

Source: HowStuffWorks

Answer 2

A wind vane measures wind direction, not wind speed. To measure wind speed, an anemometer is used. An anemometer typically uses rotating cups or propellers to determine wind speed based on how fast they spin.