If you’re reading this, it’s safe to say you’ve experienced rain. But have you ever wondered where rain comes from or how fast it can travel through the sky? Whether you love the soothing sounds it brings or loathe how it can ruin a perfectly good hair day, there’s a whole lot more to those little droplets of water than meets the eye.
Rain drops are formed high in the sky when water vapor in a cloud condenses and turns into liquid. The liquid masses cling to small particles in the atmosphere and form minuscule water droplets. The droplets then makes their way through the clouds and consume other droplets. Think of it like the atmospheric edition of Pacman. Once a single water droplet hits .004 milligrams in weight, it has officially earned the title of rain drop (and bragging rights, of course).
A falling object achieves maximum speed when it reaches terminal velocity. This is when the force of air resistance pushing upwards perfectly balances out with gravity pulling downwards. For a raindrop measuring .08” in diameter, terminal velocity is achieved at around 15 mph. To compare, a skydiver’s terminal velocity clocks in at approximately 120 mph, meaning a human falls through the sky 8 times faster than a raindrop does.
The smaller a raindrop, the slower it’s going to fall through the atmosphere. During a light drizzle, the raindrops are so tiny that they reach terminal velocity at a mere 5 mph. You might think that sounds impossibly slow, but it’s actually the same speed as someone on a jog.
Here’s a look at how raindrops, snowflakes, and hail measure up to each other in regards to terminal velocity:
It’s pretty interesting to learn where rain comes from and how fast it falls, isn’t it? Next time you go jogging, remember you’re traveling at the same speed of a raindrop… it might be the motivation you need to pick up the pace. Learn more about the formation and speed of rain here: