Do you know what the difference is between hail and snow? Both are little pieces of ice falling from the sky, so what makes them different? Keep reading to find out!
You may hear adults talk about how many inches of snow fell during a snowstorm. Do you think that's the same as how many inches of water fell? Try this experiment and find out! (If you don't have snow where you live, you can still have fun making your own crystal snowflakes!)
Snow is made when water freezes in the form of ice crystals that we call snowflakes. The pointed star-like shape of a snowflake causes its points to stick out far from its body, allowing the snowflake to take up a lot of room. (If you stick your arms straight out from your body, something similar would happen with you! Your arms cause your body to take up more space and you may find yourself bumping into walls or having a hard time making your way down a hallway with your arms sticking straight out.) When lots of snowflakes pile up, their points keep them from getting very close together, creating empty space in between the snowflakes. When the snow melts into water, the snowflakes no longer have their points, and the space between them disappears. (If you put your arms down next to your body, you are no longer taking up so much space and can get much closer to other people and things.) So the melted snow takes up less space as water than it did as snowflakes.
Hailstones are chunks or balls of ice that sometimes fall during thunderstorms. To find how this happens, read our Teacher Tidbit section on hail. Have you ever heard of golf-ball-sized hail? Or maybe you have heard of pea-sized hail. Where do people get these strange names for hail? Try this experiment to get an idea of how hail sometimes gets weird names.
Gather as many of the following objects as possible:
For older kids:
When a hailstorm hits an area, it's hard not to notice the pieces of ice suddenly falling from the sky. Depending on the storm, these pieces of ice can range in size from very small to very large. Knowing the size of the hail is important because it gives us an idea of how strong the storm is that made the hail. In general, the larger the hail, the stronger the storm. The common objects that you used in the activity represent common hailstone sizes.
If you have ever tried to guess the size of hailstones in inches, you may have found that hard to do - most people do. Getting an accurate size of the hailstones is tricky unless you have a ruler handy to measure whenever a storm happens, plus hail usually melts quickly since it comes with summer storms and warm temperatures. To make it easier, we usually estimate the size of hailstones by comparing them to common round objects, like the ones listed above. The next time you experience a hailstorm, go outside after the hail has stopped falling and see if you can find any hailstones left on the ground. Then think of as many objects as you can that the hail is similar in size to.
Have you ever wondered how much water is in snow or why sprinkling salt on walkways and roads helps ice melt away? January is a cold month for many of us, but even if there isn’t any snow where you live, you can still experiment with ice!
You may have noticed people sprinkling chunks of salt on the sidewalks or roads during the winter to help melt ice. Learn why salt melts ice in this cool experiment.
As we discovered in the snow experiment, water freezes and ice and snow melt at 32 degrees Fahrenheit. This is known as the freezing point of water. Salt (scientific name: sodium chloride) lowers the freezing point of water. When that happens, ice will melt at a lower temperature than normal. That’s exactly what happened in this experiment.
When you poured salt on top of the ice cubes in the glass of water, they started to melt almost instantly because the salt lowered the freezing point of the ice. In other words, once you added the salt, the glass would have had to get a lot colder to keep the ice frozen since salt makes ice melt at a lower temperature. Some of the ice around the string started to melt almost immediately. However, after a few minutes, the small amount of salt you added began to be dissolved into the water around the ice, which caused the freezing point on the surface of the ice to go back to normal. When that happened, some of the water re-froze around the ice, freezing the string to it, too!
Play with salt and ice some more with this pretty project.
As we discussed in the previous experiment, table salt lowers the freezing point of water. In this case, it means the salt makes the ice start to melt almost right away. Adding colors on top of the salted ice allowed you to see the effect salt had on the ice a little better. Notice how the salt formed cracks and holes down the sides of the ice chunk and made the top part seem a little slushy? If you’d like, you can add more salt to some of the ice and check back periodically to see which ice melts faster—the one with just a little salt, or the one with more salt
Snow forms in the clouds when water vapor freezes into ice crystals - what we call snowflakes. While many clouds can produce snow, dark nimbostratus clouds are usually the best snow makers. These clouds are full of water, which makes them look very dark. If it is warm outside, rain will fall from them, but if it is cold enough, snow will fall. These clouds block out sunlight and make the sky look solid gray.
Snowflakes come in a large variety of shapes, but all snowflakes have six sides. On some snowflake shapes it is very easy to see all six sides, but on other shapes it is a bit harder to see them. Here are some of the most basic shapes:
If it is snowing outside, go out and try to identify the shapes of the snowflakes. Try catching the snowflakes on a sheet of black construction paper so that they are easier to see. Just leave the paper outside for a few minutes first to let it cool down so that the snowflakes don't melt as quickly! Snowflakes can take on lots of different shapes, including combining some of the basic snowflake shapes. As you are looking at the snowflakes, notice the patterns made in them. You should notice that they make identical (or very close to identical) patterns on all of the points of the star. If you could fold a snowflake in half, you would see that both sides of the snowflake would match up. This is called symmetry. If you find a snowflake without six sides, it was probably damaged by strong winds or bumping into other snowflakes while it was falling. These snowflakes are sometimes called irregular snowflakes, because it is hard to tell what type of shape they were originally.
Hail forms when very strong winds push drops of water high up in the air where it is very cold. This causes the water to freeze into balls of ice called hail. When the hail gets too heavy for the wind to keep it up in the air, it falls to the ground. Because hail needs very strong winds to form, it usually comes with tornadoes and thunderstorms that happen in the warm spring and summer months. Imagine having little balls of ice on the ground while it is warm outside!
The individual pieces of hail are called hailstones. The size of a hailstone is often described using names of common objects that are close to the size of the hailstones. For example, pea-sized hail is the size of peas and golf-ball-sized hail is about the size of golf balls. Hail is usually small, but it is not impossible for grapefruit or softball sized hail to fall when the weather conditions are just right! To learn more about hail sizes, do the Naming Hailstones science project.
Huge cumulonimbus clouds (like the ones in the picture), also known as thunderheads, produce hail. If you see these clouds in the sky, there is a good chance that a hailstorm may be coming your way. Hailstorms do not last very long - only about 5-10 minutes - but that is long enough to damage buildings, cars, and farmers' crops. Some places get hailstorms that can leave over a foot of hail on the ground! If it ever starts hailing where you live, get inside quickly and stay away from windows that may get broken by the falling hail.
Water Vapor - when water from the Earth evaporates into the air, it becomes a gas and is called water vapor.
Hexagonal - a shape that has six sides.
Symmetry - a shape has symmetry if it can be folded in half and the two sides match up perfectly.
Use this Snow and Hail worksheet to review the names of snowflakes and sizes of hailstones through matching and coloring.