Why do raindrops fall

This is a frictional force. Unlike friction between rigid bodies, this fluid friction depends on the relative velocity between the surfaces. That means as the speed of raindrops increases, the fluid friction also increases. So the forces on the raindrop now are buoyancy and gravitational force which are constant and fluid friction which is increasing.

When the speed of raindrop increases so high that the fluid friction is equal to the gravitational force-buoyancy force, the net force on the raindrop finally becomes zero. Now the drop does not accelerate anymore, hence the speed of the drop is saturated.

There is a really nice answer by Farcher, I am submitting my answer because I believe in certain cases a picture is more then words, and to add some interesting facts.

In your case, the raindrop does the same thing, it skydives, first, it accelerates, until increasing air resistance cancels gravity acceleration , after which point the raindrop falls at a steady speed because air resistance and gravity acceleration are in equilibrium. The net force doesn't become zero at the start ,it takes some time. If you consider theoretically the drag is like an exponential decay and it dies out at infinity. As the velocity increases, Drag force increases as a square term.

So at one point, the net force acting is zero, it won't accelerate, it's falling, it's velocity doesn't change. Consider the moment when the net force becomes zero, at that moment, it is falling, if it was to stay put at that moment, then a huge force must act in the direction opposite to which it is falling ,but there is no such force, drag doesn't achieves this, because it has an important job of tackling the gravity.

So there is no new force ie only two forces are acting Drag and Gravity. Consider a space where there is no atmosphere and no gravity due to any planet, if we throw a ball does it stop or does it move continuously?

We can certainly say that if it were to stop, it is due to some kind of force, we aren't giving any force, so it must move. This is what happens in the case of raindrop, it continues to fall because the two forces acting on it cancels out and some other force must stop it, since there isn't any other force it continues to fall.

Newton's First Law beautifully says this. An object at rest remains at rest, and an object in motion remains in motion at constant speed and in a straight line unless acted on by an unbalanced force. There is a lot going on in the cloud as the raindrop forms. Firstly you have warm moist air rising, as this column of air rises it expands pressure reduces as altitude gained and cools eventually the moisture in the air will precipitate onto any aerosols in the rising air and form a cloud.

The water droplets will coalesce and accumulate until the weight of the water droplet exceeds the updraft that is keeping it aloft - NB a kilometre wide fluffy cloud weighs in at around 6 tonnes!! Sign up to join this community.

The best answers are voted up and rise to the top. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Learn more. Why do rain drops fall with a constant velocity?

Ask Question. Asked 1 month ago. Active 21 days ago. Viewed 9k times. I came across a line that says that: Rain drop falls with a constant velocity because the weight which is the force of gravity acting on body of the drop is balanced by the sum of the buoyant force and force due to friction or viscosity of air.

I was not satisfied by the explanation So I searched the internet which too had similar explanations: The falling drop increases speed until the resistance of the air equals the pull of gravity, at which point the drop begins to fall at a constant speed, its terminal velocity. Improve this question. Provided by the Springer Nature SharedIt content-sharing initiative. Advanced search. Skip to main content Thank you for visiting nature.

Download PDF. Exploding drops produce miniature showers. You have full access to this article via your institution.

In every drop of rain, a shower. Credit: Emmanuel Villermaux. References 1 Villermaux, E. Google Scholar 3 Marshall, J. Article Google Scholar Download references. Authors Fiona Tomkinson View author publications. Rights and permissions Reprints and Permissions. About this article Cite this article Tomkinson, F. Copy to clipboard. Raindrops, along with all things that fall, drop to the Earth because of gravity. Yet, the process that raindrops undergo to get to the point where they fall is a little more complicated than a simple gravitational effect.

To become rain, water must first transform to a gas, travel up into the atmosphere and then transform back again to a liquid. Only then do the raindrops succumb to gravity and fall out of clouds. The process during which water transforms to rain and falls is known collectively as the hydrologic cycle. The hydrologic cycle is also known as the water cycle, a continuous process with no starting or ending point. The cycle involves nine parts, each having to do with what water does at any given stage of the cycle.

For instance, during the evaporation stage, the sun heats liquid water, turning it to a gas that then floats up into the atmosphere. While cartoonists typically draw raindrops in a teardrop or pear shape, raindrops are not shaped in those forms.

They are drawn as teardrops to give the image of falling through the atmosphere, which they do. As the raindrops fall they are flattened and shaped like a hamburger bun by the drag forces of the air they are falling through.

Raindrops are at least 0. You will not find a raindrop any bigger than about one-quarter of an inch in diameter; larger than that, the drop will break apart into smaller drops because of air resistance. Precipitation drops smaller than 0.