Blue hour

High school (ages 12+)
Environment & Earth

Name:

Date:

Step 1 · Read the article

Open the article and read it at the level above. Then answer the questions below in your own words.

https://smallwhale.org/articles/blue-hour

Write what each word means, using the article.

Do not copy the article. Write two things you learned, the way you would explain them to a friend.

Answers below are taken from the article’s stored facts, so they match what the student read.

1. What is the dominant atmospheric processes?Rayleigh scattering and Chappuis absorption by ozone
2. What is the latitudinal variation?Duration is significantly longer at higher latitudes due to shallower solar angles
3. Why does the sky look so blue during the blue hour?Sunlight travels a long way through the air, scattering blue light and absorbing other colors. Ozone also filters some light, making the blue richer.
4. When does the blue hour happen?It happens after sunset or before sunrise, when the sun is between 6 and 12 degrees below the horizon during nautical twilight.

Nautical Twilight: The twilight phase where the sun is between 6 and 12 degrees below the horizon, allowing celestial navigation.
Rayleigh Scattering: The elastic scattering of light by particles much smaller than the wavelength of the light, responsible for the blue color of the daytime sky.
Chappuis Absorption: The absorption of solar radiation by ozone, particularly in the visible spectrum, contributing to twilight colors.
Atmospheric Optics: The study of the optical phenomena in the atmosphere, such as rainbows, halos, and twilight colors.