Normal wind speed can vary depending on the context and location. However, there are several scales that define wind speed based on observable effects. One of the most commonly used scales is the Beaufort Wind Scale, which relates wind speed to observed conditions at sea or on land. The Beaufort Wind Scale ranges from 0 (calm) to 12 (hurricane), and each level is defined by specific visual clues and damage effects. For example, a gentle breeze is defined as having a wind speed of 8 to 12 mph, and leaves and small twigs are in constant motion.

Its important to note that wind gusts can be much stronger than the sustained wind speed, and they can cause damage even if the sustained wind speed is relatively low. The sustained wind speed is the average wind speed over two minutes, while wind gusts are sudden bursts in wind speed that typically last under 20 seconds and must be over 18 mph and at least 10 mph faster than the average wind speed to be considered a gust.

In summary, normal wind speed can vary depending on the context and location, but the Beaufort Wind Scale provides a useful way to define wind speed based on observable effects. A gentle breeze, for example, is defined as having a wind speed of 8 to 12 mph, and leaves and small twigs are in constant motion. Its also important to consider wind gusts, which can be much stronger than the sustained wind speed and can cause damage even if the sustained wind speed is relatively low.