Have you ever noticed that when there is snow on the ground the days and nights tend to be cooler? That is because snow reflects a lot of sunlight and has a high albedo. The more sunlight that is reflected, the slower the warming process is.
Snow has a very high albedo, it ranges from 0.90-0.40. You may be thinking what is albedo? Albedo indicates how well a surface reflects solar energy. If a surface reflects all the solar energy back into the atmosphere, then it has an albedo of 1. If a surface absorbs all the solar energy it has an albedo of 0. The whiter the surface the higher albedo, making the surface cooler. The darker the surface the lower the albedo, making it warmer.
Snow has a wide range in albedo. Fresh snow has an albedo of 0.90 while, melting snow is closer to 0.40. This means snow can reflect 40 to 90 percent of incoming solar energy back into the atmosphere. The less energy absorbed the harder it is to warm. The fact that snow reflects more energy than it absorbs it helps keep things cooler.
The albedo of the Earth’s surfaces ranges from 0.1-0.2 for the darker surfaces to 0.4-0.5 for lighter surfaces. This means the darker surfaces reflect only 10-20 perfect of energy and absorb the other 80-90 percent which makes them warmer. The lighter surfaces reflect 40-50 percent of the energy and only absorb 50-60 percent which makes them cooler.
The ocean has a very low albedo. Typically, the ocean surface has an albedo of .06. This means that the ocean absorbs 94 percent of the solar energy and reflects 6% back into the atmosphere.
This is why we are told not to wear dark colors during the summer months. The darker the color the more solar energy is absorbed, making you warmer. The lighter colors reflect more solar energy, keeping you cooler.
*Reminder: The closer a surface is to (1.0) the more energy it reflects, making them cooler. The closer it is to (0) the more energy is absorbed making them warmer.
Here is a list of common surfaces and their albedo value:
- New asphalt, 0.04 – 0.05
- Aged asphalt, 0.1 – 0.12
- New concrete, 0.4 – 0.55
- Aged concrete, 0.2 – 0.3
- Black acrylic paint, 0.05
- White acrylic paint, 0.8
- Green grass, 0.25
- Bare soil, 0.17
- Conifer Forest, 0.08 – 0.15
- Desert sand, 0.4