The colors of the sky can be incredible. Whether it is the colors of the clouds or the sky, shades of red, orange, blue and even purple can be seen almost every day. Do you know why the atmosphere changes colors so frequently?
The most poular reason for thinking the sky is blue is because the sun is reflecting off the ocean. Unfortunately, that is a common misconception which we have all heard at one time. The reason the sky is blue (or any color at all) is because of the sun refracting off molecules in the air. All light travels in a straight line unless it has something blocking it. If there is something in the way, it can reflect or bend in different directions. This happens to the sun's rays when it hits the atmosphere. The particles and gases in the air scatter visible light all over the atmosphere, and since blue light has a shorter / smaller wave than most of the visible light spectrum, we see the sky as mostly blue during the day. During the evening however, the sky can change colors and become red, orange, yellow, etc.
During the evening, the sky can become a fiery red because of the same process as illustrated above. However, instead of a direct/short path from the sun to our eyes, light from the sun has a long path to take and because of this, we see the longer visible waves which are typically orange/red. These colors can be exacerbated by low humidity and a high pressure system overhead. With a humid/hazy day, as the sun sets/rises, there are more particles in the air for the light to reflect making it difficult for waves to scatter, so the colors may be a bit dimmer. When there are less particles in the air and it is dry, more of the light can scatter outwards creating a vibrant sunset. During the winter when there is less moisture in the air, dawn and dusk can be more vivid. Needless to say, this can happen in the summer as well, especially if there is a dry airmass overhead.
Here is one example of a vibrant spring sunset along Lake Ontario. This happened when a cold airmass moved into the area.
Image taken by Meteorologist Bobby Bianco
The sky isn't the only thing that can change colors during the day. Clouds can turn from white to gray, sometimes even green. But since water is clear and clouds are made of tiny water droplets, why are they white? Well, it is actually quite simple. Clouds are pockets of condensed water made of cloud droplets and light from the passes through these clouds. Depending on how large the clouds are will determine how much light can pass through. If there is a dark gray cloud, it usually means the cloud is tall and the light is having a difficult time passing through the whole thing. However, this is NOT always the case. Clouds can appear gray if the sun angle is poor and not directly overhead. If the sun has a long path through a relatively thin cloud, it can appear gray. Now, what makes them green? Typically, if there is a "greenish" tint to a cloud it can mean a few things.
1. Get indoors because that is most likely a very strong storm moving towards you.
2. This cloud most likely contains large raindrops and perhaps even large hail.
3. There is a potential for a tornado because it is a strong storm and may be a supercell moving overhead. (Though not every time)
Once again, if there is a green cloud, the sun is most likely reflecting off the rain drops and large hail in such a way that it turns a green color. It is similar to snow when there are large piles or even icebergs. The snow and ice turns a blue/green color because of the way the sun is reflecting off of it.
Remember to always look up! You never know what you will see in the sky.
An example of how a severe thunderstorm with hail (but no tornado) can result in a green tint to the clouds. Also, you can see there is a lot of water in the clouds based on how dark they are.
Image taken by Meteorologist Bobby Bianco
