Colours of Our Atmosphere
Colours of our Atmosphere You can see three prominent colours in this image, viz. White, Blue and Green. The white is coming from the clouds formed in our atmosphere, which in this case happen to be below the plane. The clouds formed by the condensed water vapour, are highly reflective and reflect Sunlight and are white. Wait, in this image it is not the sunlight, but moonlight! Doesn't matter, its still sunlight reflecting from the Moon. The blue colour is again coming from our atmosphere. It looks blue because of the phenomena of Raleigh Scattering. Particles in atmosphere scatter sunlight in all directions. Blue light is scattered more than other colors because it travels as shorter, smaller waves. This is why we see a blue sky most of the time. The source of light is moonlight. Oh! again its the sunlight. The green colour is coming from the aurora & air-glow activity in the atmosphere. Air-Glow is caused by collisions between fast-moving particles (electrons) from space and the oxygen and nitrogen gas in our atmosphere. These electrons originate in the magnetosphere, the region of space controlled by Earth’s magnetic field. As they rain into the atmosphere, the electrons impart energy to oxygen and nitrogen molecules, making them excited. When the molecules return to their normal state, they release photons, small bursts of energy in the form of light. The color of the aurora depends on which gas is being excited by the electrons. Oxygen usually emits a greenish-yellow light. This image was shot from a plane window flying from Delhi to New York on 6th November 2020. At the time of this image the plane was over Greenland. There's Venus shining brightly near the horizon. The constellations of Coma, Virgo, Leo, Hydra and others can be seen in the image.