Blue and Red Sky

When someone asks us what is the colour of the sky?..We immediately reply them, it is blue colour. Yes, most of the time the sky is blue, but at the time of dawn and dusk the sky will be in different shades of red. All of us have noticed this, but we rarely know the reason.

So, let's get to know why this happens?...

This happens mainly because of scattering of the sun rays (light). When the sun rays pass through the earths atmosphere, it gets scattered due to the gas molecules or particles present in the atmosphere.

The white light that we receive from the sun, has colours like a rainbow, that some of us might have seen in our physics class through a prism as shown in Fig. 1.

Fig. 1. White light through a Prism

Source: https://spaceplace.nasa.gov

Normally, among these rainbow colours, blue scatters the most and red scatters the least. So, except at the time of sunset and sunrise the sky colour on a clear day will be blue in colour. This is because the blue colour is scattered by the atmosphere and reaches us. So we see a blue sky.

You might be thinking so blue scatters and blue sky, but then why red shades at dawn and dusk?...

When the sun is far from us, the light has to travel a long distance, and when it reaches us, the blue colour is scattered completely and we will be seeing red colour and hence shades of red sky at sunrise and sunset.

Source: https://explainingscience.org/

Watch the video for your crispy understanding.

Source: https://spaceplace.nasa.gov/blue-sky/en/

Now we understood the reason for blue and red sky, to know more about scattering of light and colour of sky try reading about Rayleigh and Mie scattering, This is to make you familiarize with the terms that is used in the weather science.

Stay tuned to know about the weather science that mesmerizes us....