In a rainstorm with a strong wind, what determines the best position in which to hold an umbrella?

It is best to hold the umbrella at an angle which is parallel to the direction of rain drops.

Explanation:

Velocity of vector of rain drops plays crucial role here. Direction of the wind causes the rain drop directions. Hence handle of the umbrella should be parallel to the direction of rain drops. there will be more umbrella area if we keep umbrella in the direction.

The best way to hold a strong umbrella in rainstorm with a strong wind will be against the direction of the wind. This can provide with the maximum protection in rain. Moreover, it should be placed slightly upward also, at an angle. This will again call for maximum protection.