Fluids tend to move from areas of abundance to areas of deficits - think of siphoning gas from a car. The difference in pressure between two locations is called a pressure gradient , and a pressure gradient force will cause air to move from high pressure to low pressure. Wind direction is measured with a wind vane. Remember, winds are always named after the direction from which they are coming . Hence, an southeasterly wind describes winds coming from the southeast.
Speed is measured with an anemometer , a device with cups that turn during a wind.
The faster the rotation the more electric current is generated, which is then converted to mph. Land and Sea Breezes These are excellent, simple examples of the effects of unequal heating. Remember - water heats and cools more slowly than land surfaces. A basic principle we learned earlier. During the day, land will heat up more rapidly than an adjacent body of water, causing unequal heating.