# Change in appearance of liquid drop due to gravity

A liquid drop is spherical in shape due to surface tension. But why does it appear as a vertical line under the free-fall due to gravity? (E.g. During a rain - falling raindrop) Is there a specified length for the line or does it vary with the size of drops?

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Your original question was better--- they appear long because they are moving fast, and so streak in your eye. – Ron Maimon Aug 9 '12 at 8:32
I'm not sure I exactly understand your question but maybe that can be interesting ems.psu.edu/~fraser/Bad/BadRain.html – aberration Nov 2 '12 at 14:51

Edit: Regarding the appearance of raindrops (as opposed to their physical shape), consider taking a photograph of falling rain. The camera integrates the incoming light over the exposure time $t$, during which the drop travels a distance of $v t$, where $v$ is the velocity. If we are close to the ground this will be the terminal velocity, which is about $2_{m/s}$. If we use an exposure time of $t=1/60_s$ (say we are using a flash), the drop will trace a line of length $\sim 3_{cm}$. The apparent line on the photograph then has to account for distance from the drop, etc.