The relation between intensity of wind pressure P and velocity of wind V is taken as A. $${\text{P}} \propto {\text{V}}$$ B. $${\text{P}} \propto {{\text{V}}^2}$$ C. $${\text{P}} \propto \frac{1}{{\text{V}}}$$ D. $${\text{P}} \propto {{\text{V}}^{\frac{1}{2}}}$$

The correct answer is $\boxed{\text{B. }{\text{P}} \propto {{\text{V}}^2}}$.

The intensity of wind pressure is proportional to the square of the velocity of the wind. This is because the faster the wind blows, the more air molecules are hitting a given surface per unit of time. The force of each impact is small, but the cumulative effect of many impacts can be significant.

Option A is incorrect because the intensity of wind pressure is not directly proportional to the velocity of the wind. Option C is incorrect because the intensity of wind pressure is not inversely proportional to the velocity of the wind. Option D is incorrect because the intensity of wind pressure is not proportional to the square root of the velocity of the wind.