From the Earth’s surface, there is an unhindered view of the sky.
The term “sky” is frequently used colloquially to describe a view from the surface of the Earth, but its usage and meaning can change. A little portion of the sky that resembles a dome can be see an observer on Earth’s surface.
Etymology Etymology The word “sky” is derived from the Old Norse word “sky,” which means “cloud, God’s habitation.”
. Middle English references eventually limited it to its modern, religious meaning. 
The majority of the light in the daytime sky, with the exception of direct sunlight, is produced via scattering, which is mostly a small-particle limit known as Rayleigh scattering. When light is coming from an object, such as an object in the air, the scattering caused by molecules-sized particles is stronger in directions both toward and away from the object than it is in directions perpendicular to the incidence path.  The Sun is the source of all visible light, therefore scattering affects light at all visible wavelengths, but it is most pronounced at the shorter (bluer) end of the visible spectrum. Having lost some of its shorter-wavelength components, the remaining direct sunlight seems a little less blue.
Additionally, clouds experience significantly stronger scattering. White light refracted by individual water drops to create a series of
Over the course of a day, the sky’s brightness and hue change significantly, and their main causes also change. Direct scattering of sunlight (Rayleigh scattering) is the overwhelmingly dominant source of light when the Sun is high above the horizon. The issue is more complicated during twilight, which is the time between sunset and night or between night and daybreak.
When a green spot is visible above the Sun, usually for no longer than a few seconds, or it may resemble a green beam shooting up from the sunset point, these optical phenomena known as green flashes and green rays occur. Green flashes are a category of occurrences that have a variety of origins, most of which are
Ø During the night:
The sky as viewed at night ireferred to as the “night sky. ” The phrase refers to views of celestial objects like stars, the Moon, and planets that become visible. It is a used in connection with astronomy and skygazing. Depending on the location and the time of day, moonlight, stars, and airglow are examples of natural light sources in the night sky. It is simple to see that the night sky is not completely dark. One would not be able to perceive an object’s shadow against the sky if the sky were completely dark (in the absence of the moon and city lights).
Use in weather forecasting:
One of the more crucial factors used to predict weather in hilly places, along with pressure tendency, is the state of the sky. Rain is likely to fall soon if the cloud cover gets thicker or a higher cloud deck invades. Halos around the Moon can form at night amid high, thin cirrostratus clouds, signalling the approach of a warm front and the accompanying rain.  A marine layer, a sign of a stable environment, might connected to morning fog, which heralds favourable weather.  Wind or clouds that foreshadow rain impede the production of fog. A line of thunderstorms moving in could be a sign of an impending cold front. The absence of clouds is a sign of good weather in the near term. 
Use in transportation:
Flight is the process of an object moving through or beyond the sky (as in spaceflight), without any direct mechanical support from the ground, whether by creating aerodynamic lift, propulsive drive, aerostatically employing buoyancy, or by ballistic movement. Aeronautics, the study of vehicles that travel through the air, astronautics, the study of vehicles that travel through space, and ballistics, the study of projectile flight, are the three subfields of aerospace engineering that examine the engineering aspects of flight.
Significance in mythology
There are gods who are par
ticularly associated with the sky in several mythology. The sky revered in Egyptian religion as the god Horus and the goddess Nut.
Atahensic was a heaven goddess who descended to the earth during the creation of the Earth in Iroquois mythology. Numerous cultures have depicted constellations as lines between stars in the sky and used them in myths and legends about their gods.
The moon illusion: I. How high is the sky? published in 1982 by J. C. Baird and M. Wagner. General Journal of Experimental Psychology, 111(3), 296-303, doi:10.1037/0096-3418.104.22.1686, pmid 6215460
John Tyndall (December 1868). On the Blue Color of the Sky, Skylight Polarization, and General Light Polarization by Cloudy Matter 17: 223–33. Proceedings of the Royal Society. JSTOR 112380. Bibcode:1868RSPS…17..223T. doi:10.1098/rspl.1868.0033.