Have you ever wondered what it’s like to be a raindrop? I recently went indoor skydiving, and it gave me a new perspective on how raindrops fall through the sky. It was such an amazing experience, and I can’t wait to do it again!
When you think of a raindrop, you probably imagine a teardrop shape, right? That’s how we’ve been drawing them since we were little. But guess what? That’s not what raindrops actually look like when they’re falling!
When water drips from a faucet, it does briefly take on a teardrop shape because the tail of the drop drags behind. But as soon as the drop separates, it becomes more like a blob. This happens because of something called surface tension. Surface tension is when water molecules stick together more than they stick to the air around them. This makes the drop form a shape with the smallest surface area for its volume, which is a sphere. However, raindrops aren’t perfect spheres either.
As raindrops fall, they move quickly and face air resistance. Air is a fluid, which means it flows around objects. If you’ve ever stuck your hand out of a moving car, you’ve felt the air pushing against it. The same thing happens to raindrops as they fall through the atmosphere.
Several forces act on a raindrop: gravity pulls it down, air molecules push it up, and the water molecules hold it together. These forces flatten the raindrop into a shape that looks more like a hamburger than a teardrop.
We can’t just fly up into the sky to look at raindrops, but we can recreate the conditions here on Earth. By using a vertical wind tunnel, we can suspend droplets in the air and observe them. This setup mimics the forces a raindrop experiences as it falls.
When an object falls, it speeds up until the air resistance equals the force of gravity. This is called terminal velocity. In a wind tunnel, the air pushes up against the object, balancing the forces just like when a raindrop falls at terminal velocity.
Real raindrops can look like spheres, burger buns, pancakes, or even parachutes. A long time ago, a farmer named Wilson Bentley collected raindrops in pans of flour to study their size. He found that most raindrops are small when they reach the ground.
Another scientist, Philipp Lenard, used a wind tunnel to study raindrops. He discovered that the largest drops don’t stay big for long. Small cloud droplets start as spheres, but as they fall, they collide and combine into larger drops. These larger drops have more surface area for air to push against, causing them to flatten. When a drop gets to about five to six millimeters in size, it changes from a bun shape to a parachute shape. If it grows even more, it can break apart into smaller drops.
It’s hard to say exactly how big a raindrop can get, but they usually don’t get bigger than seven millimeters before breaking apart.
So, next time you think of rain, remember that raindrops are more like pancakes and hamburgers than teardrops. I hope this doesn’t ruin your childhood drawings! Keep exploring and stay curious!
Using clay or playdough, create models of raindrops in different shapes such as spheres, hamburger buns, and parachutes. This will help you visualize how raindrops change shape as they fall. Share your models with the class and explain the forces that cause each shape.
Conduct a simple experiment by dropping water droplets from a height onto a flat surface. Observe and record the shape of the droplets upon impact. Discuss how surface tension and air resistance might affect their shape during the fall.
Watch a video or demonstration of a wind tunnel experiment. Pay attention to how droplets behave in the wind tunnel and compare it to their behavior in the atmosphere. Discuss how scientists use wind tunnels to study raindrops.
Research the maximum size of raindrops and what factors influence their size. Create a poster or presentation to share your findings with the class, including how raindrops can break apart when they become too large.
Draw or paint a series of raindrops in various shapes based on what you’ve learned. Use your artwork to illustrate the journey of a raindrop from a cloud to the ground, highlighting the changes in shape due to different forces.
Here’s a sanitized version of the transcript:
—
I just finished indoor skydiving! It was an incredible experience, and it gave me a unique perspective on what it’s like to be a raindrop. When you think of a raindrop, you might be picturing it incorrectly. But before we dive into that, I’m definitely going back for more because it was so much fun!
If I asked you to draw a raindrop, most of you would probably sketch something like this. That’s how we’ve been drawing them since childhood, right? But this representation is not accurate. A falling raindrop doesn’t actually look like that; it’s physically impossible.
When water drips from a faucet, each drop does take on a teardrop shape for just a moment as its tail drags behind. However, very quickly, the drops become more blob-shaped. This change occurs because of surface tension. Surface tension arises because water molecules are more attracted to each other than to the air around them. Once the drops separate from the faucet, they form the shape with the smallest surface area for their volume, which is a sphere. Therefore, raindrops can never maintain that classic teardrop shape, but they also aren’t perfect spheres.
Raindrops fall quickly, which means they are affected by air resistance. Air is a fluid, though it’s not wet in the way we typically think of fluids. In physics, a fluid is any substance that deforms or flows around an object when that object pushes against it. If you’ve ever held your hand outside a moving car, you’ve felt the air flow around your hand. The air also exerts a force against your hand, and to keep your hand still, your muscles must exert an equal force in the opposite direction. This is similar to what happens when water falls through the atmosphere.
Several forces act on a raindrop at once: gravity pulls it down, collisions with air molecules provide an upward force, and attractive forces between water molecules hold the drop together. These combined forces flatten the spherical drop into a shape that resembles a hamburger.
But how do we know what raindrops really look like? We can’t exactly go up into the sky with a magnifying glass to examine them, but we can simulate the conditions here on Earth using a large fan. In a vertical wind tunnel, droplets are suspended in the air, experiencing the same net forces as falling raindrops. Instead of the droplets falling and hitting the air, the air rises and interacts with the droplets.
As an object begins to fall due to gravity, it accelerates, increasing its velocity until the force of air resistance equals the force of gravity. At this point, it stops accelerating, and this is known as terminal velocity. Different objects have different terminal velocities based on their surface area and mass.
In the wind tunnel, I can float because of the opposing forces: gravity pulling me down and the upward force from the air. An object floating in a wind tunnel experiences the same net forces as an object falling at terminal velocity. When we suspend a droplet of water in the wind tunnel, we observe what we would see if we were falling through the air next to a raindrop at terminal velocity. What we see is definitely not the classic shape we drew as kids.
Real raindrops come in four rough shapes: spheres, burger buns, pancakes, and parachutes. Around 1900, a farmer-turned-amateur scientist named Wilson Bentley began collecting raindrops in pans of flour to measure their size. He studied 70 different rainstorms and found that, regardless of conditions, most raindrops that reach the ground are small.
At the same time, German physicist Philipp Lenard developed a method to observe raindrops as they fell by building a vertical wind tunnel. He discovered that the largest drops don’t stay big for long. The smallest cloud droplets start as spheres, but as they fall, small drops collide and combine into larger ones. These larger raindrops have more surface area for air to push against, causing them to flatten out even more. Once a drop reaches about five to six millimeters in size—similar to a housefly—it changes from a bun shape to a parachute shape. As it continues to grow, it can break apart, as the force from the air becomes greater than the attraction between the water molecules, scattering into smaller, rounder drops.
So, how big can a raindrop be? That’s difficult to determine, but tests show they rarely exceed seven millimeters in diameter before breaking apart.
In conclusion, physics tells us that rain is more like pancakes and hamburgers than teardrops. I hope I didn’t ruin your childhood! Stay curious!
—
This version maintains the original content’s essence while ensuring it is appropriate for all audiences.
Raindrop – A small drop of water that forms in the atmosphere and falls to the ground as rain. – Example sentence: Scientists study how the shape of a raindrop affects its speed as it falls to the ground.
Surface – The outermost layer or boundary of an object or material. – Example sentence: The surface of the water in a glass is flat when it is at rest.
Tension – A force that stretches something tight, such as the force that acts on the surface of a liquid. – Example sentence: Surface tension allows small insects to walk on water without sinking.
Gravity – The force that attracts objects toward the center of the Earth or any other physical body having mass. – Example sentence: Gravity is the reason why objects fall to the ground when dropped.
Air – The invisible mixture of gases that surrounds the Earth and is essential for life. – Example sentence: Air resistance slows down a parachute as it falls to the ground.
Resistance – A force that opposes or slows down motion through a medium, such as air or water. – Example sentence: Engineers design cars to reduce air resistance and improve fuel efficiency.
Velocity – The speed of an object in a specific direction. – Example sentence: The velocity of a car increases as it accelerates down the highway.
Shape – The form or outline of an object. – Example sentence: The shape of an airplane’s wings helps it to lift off the ground.
Molecules – The smallest units of a chemical compound that retain the properties of that compound. – Example sentence: Water molecules are made up of two hydrogen atoms and one oxygen atom.
Study – The act of examining or investigating something in detail to understand it better. – Example sentence: Scientists study the effects of gravity on different planets to learn more about the universe.
