Have you ever wondered how rainbows form? It’s pretty cool! When light enters tiny water droplets, it bends, bounces, and bends again, creating the colorful arcs we see in the sky. But there’s something even more fascinating than rainbows that you might have seen around the sun or the moon—a bright halo or a colorful display. Let’s dive into this icy wonder!
High up in the atmosphere, where it’s super cold and dry, ice crystals form in a unique way. Instead of becoming the snowflakes we know, these ice crystals can act like tiny prisms. When they are positioned between you and the sun, often inside cirrus clouds, they create stunning halos. How does this happen?
Inside these high clouds, ice crystals are arranged in various directions. When light passes through them, it bends towards your eyes. The different orientations of the crystals refract light at different angles, but most of the light bends at about 22 degrees, making the halo brightest at that point. There’s also a dark area in the center because no light bends at less than 21.7 degrees.
When the sun is lower in the sky, even more amazing things can happen. Some ice crystals look like six-sided shapes, similar to autumn leaves. These crystals tend to fall with their flat sides down due to air resistance. Near the horizon, they are oriented the same way, focusing the light in specific spots. This can create the illusion of three suns in the sky!
These optical illusions are called sun dogs. Just like in a rainbow, longer wavelengths of light bend slightly less, giving the inside of a sun dog a red tint and the outside a blue tint.
Sometimes, you might see a ring stretching around the entire sky. This happens when flat ice crystals reflect light like mirrors. This phenomenon can even occur around the moon, creating a magical sight!
These are just a few examples of the incredible things that happen when light interacts with ice. If the conditions are just right, it can look like an artist has painted the sky with icy brushstrokes.
With clouds, sunsets, rainbows, and all this icy beauty, it can be tough to pick a favorite atmospheric phenomenon. Luckily, you don’t have to choose. Enjoy them all and keep looking up—just remember not to stare directly at the sun. Stay curious and keep exploring the wonders of our sky!
Gather some clear plastic sheets and a flashlight. Cut the plastic into small hexagonal shapes to mimic ice crystals. Shine the flashlight through them at different angles to see how light bends and creates halos. Try to recreate the 22-degree halo effect. Share your findings with the class!
Using a shallow dish of water and a flashlight, simulate the effect of sun dogs. Place the flashlight at a low angle to mimic the sun near the horizon. Observe how light refracts through the water and creates colorful patterns. Discuss how this relates to the formation of sun dogs in the sky.
Keep a daily journal of the weather and sky conditions for a month. Note any occurrences of halos, sun dogs, or other optical phenomena. Include sketches or photos if possible. At the end of the month, present your observations and discuss any patterns you noticed.
Create artwork inspired by ice halos and sun dogs. Use colored pencils, watercolors, or digital tools to depict these phenomena. Focus on capturing the colors and shapes you might see in the sky. Display your art in the classroom and explain the science behind your creation.
Use an online tool or app to explore different atmospheric phenomena. Identify when and where ice halos and sun dogs are most likely to occur. Share interesting facts and images with your classmates. This will help you understand the conditions needed for these beautiful displays.
Sure! Here’s a sanitized version of the transcript:
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[MUSIC] “This episode is brought to you by Squarespace.”
Do you remember how rainbows form? There are many videos that explain them. The physics is quite simple. Light enters tiny water droplets, bends or refracts, bounces, bends again, and different colors end up in your eye. Easy, right?
But if you’ve ever looked up in the sky and seen a bright halo around the sun or the moon, or a vibrant display of colors… that’s not a rainbow. It’s even more fascinating. In fact, you might even say… it’s ice cold.
[MUSIC]
In a previous video, we discussed the science of snowflakes and how the shape of H2O gives frozen water crystals a six-sided symmetry all the way down to the atomic level. However, way up in the atmosphere, where it’s cold and dry, instead of forming the snowflakes you might recognize, ice crystals take on a different form.
These crystals can act like tiny prisms, and if they are positioned between you and the sun, like inside a cirrus cloud, they can create those stunning halos. So how does this occur? Inside that high cloud, there are prisms arranged in various directions. If we zoom in on a slice, crystals in different positions will be oriented just right, allowing the light coming out the other side to be bent towards your eye.
Different orientations refract light at different angles, but since those angles average about 22˚, the halo appears brightest right there. And since no light is bent at less than 21.7˚, we see a dark area in the center.
When the sun is lower in the sky, even more interesting phenomena can occur. Instead of prisms, some ice crystals resemble six-sided shapes. Similar to autumn leaves, they tend to fall with their flat sides down due to air resistance. This means that close to the horizon, those crystals are oriented the same way, leading to more concentrated refraction in specific spots. It can look like there are three suns!
Because these optical illusions follow their sun master through the low sky, we refer to them as sun dogs. You know how in a rainbow, longer wavelengths are bent slightly less? That occurs here too, giving the inside of a sun dog a slight red tint and the outside a slight blue tint.
On rare occasions, you can see a ring stretching around the entire sky. Instead of refraction, those flat ice crystals reflect light like mirrors. This phenomenon can even happen around the moon!
These are just a few of the incredible things that can happen when light interacts with ice. If the conditions are just right, it can look like an artist has whimsically painted the sky with icy brushstrokes.
With clouds, sunsets, rainbows, and all this icy beauty, it can be challenging to choose a favorite atmospheric phenomenon. Fortunately, you don’t have to. Enjoy them all.
Keep looking up, just not directly at the sun. Stay curious!
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Let me know if you need any further modifications!
Ice – Ice is the solid form of water, which forms when water freezes at 0 degrees Celsius or below. – In winter, ice can form on lakes and rivers, creating a solid surface.
Halos – Halos are optical phenomena produced by ice crystals creating bright circles or arcs around the sun or moon. – We saw a beautiful halo around the sun, which was caused by ice crystals in the atmosphere.
Light – Light is a form of energy that travels in waves and can be seen by the human eye. – When light passes through a prism, it splits into a spectrum of colors.
Crystals – Crystals are solid materials whose atoms are arranged in a highly ordered, repeating pattern. – Snowflakes are made of ice crystals, each with a unique shape.
Sun – The sun is the star at the center of our solar system, providing light and heat to Earth. – The sun’s energy is essential for life on Earth, driving weather and climate.
Dogs – In the context of atmospheric phenomena, “sun dogs” are bright spots that appear on either side of the sun, caused by the refraction of sunlight by ice crystals. – Sun dogs are often seen when the sun is low in the sky and there are ice crystals in the atmosphere.
Atmosphere – The atmosphere is the layer of gases surrounding Earth, essential for life and weather patterns. – The Earth’s atmosphere protects us from harmful solar radiation.
Refraction – Refraction is the bending of light as it passes from one medium to another with a different density. – A straw looks bent in a glass of water due to the refraction of light.
Angles – Angles are the space between two intersecting lines or surfaces, measured in degrees. – The angle at which light hits a surface can affect how it is reflected or refracted.
Phenomenon – A phenomenon is an observable event or occurrence, especially one that is unusual or interesting. – The northern lights are a natural phenomenon caused by particles from the sun interacting with Earth’s atmosphere.
