The correct answer is A. 4.8 kmph.
The calm period is the percentage of time during which the wind intensity is less than 4.8 kmph. This is the definition of a calm wind, according to the Beaufort scale. A calm wind is a light breeze that is barely noticeable. It is often described as a “gentle breeze” or a “light air.”
The Beaufort scale is an empirical measure that relates wind speed to observed conditions at sea or on land. It is commonly used by sailors, fishermen, and other mariners to estimate wind speed and to predict the weather. The scale is divided into 12 categories, ranging from calm (0 knots) to hurricane (120 knots).
The calm period is an important factor to consider when planning outdoor activities. A calm wind can make it difficult to sail or row, and it can also make it difficult to hear or see other people. If you are planning to be outdoors in a calm wind, it is important to be aware of the potential hazards and to take precautions to stay safe.
Here is a brief explanation of each option:
- Option A: 4.8 kmph is the definition of a calm wind.
- Option B: 6.4 kmph is a light breeze.
- Option C: 8.0 kmph is a gentle breeze.
- Option D: 9.6 kmph is a moderate breeze.