The Origin of Blue Sky
Do you know why our skies have predominantly blue in color? The richness of colors we see in our world are emitted by the light. The dimensional frequency separates the visible and invisible light in the electromagnetic spectrum in our skies. There are two types of light, the visible and invisible light. Beyond the visible light, the ultraviolet level in the electromagnetic spectrum has the bluish of blue in color. Our eyes have three color receptors (red, green and blue) all are sensitive to ultraviolet (UV) light, with predominantly on the blue side of the spectrum.
Earth's Atmosphere
An atmosphere is a layer of gases surrounding a planet or other material body that is held in place by the gravity of that body. An atmosphere is more likely to be retained if its gravity is high and the atmosphere's temperature is low.
The atmosphere of Earth is mostly comprised of nitrogen. It also contains oxygen used by most organisms for respiration and carbon dioxide used by plants, algae, cyanobacteria for photosynthesis. The atmosphere helps protect living organisms from genetic damage by solar ultraviolet radiation, solar wind and cosmic rays. Its current composition is the product of billion of years by chemical modification of the paleoatmosphere by living organisms.
Earth's atmosphere consists of a number of layers, summarized in the diagram, that differ in in properties such as composition, temperature and pressure.
The lowest layer is the troposphere, which extends from the surface to the bottom of the stratosphere. Three quarters of the atmosphere's mass resides within the troposphere, and is the layer within which the Earth's weather develops.
The depth of this layer varies between 17 km at the equator to 7 km at the poles. The stratosphere, extends from the top of the troposphere to the bottom of the mesosphere, contains the ozone layer. The ozone layer ranges in altitude between 15 and 35 km, and is where most of the ultraviolet radiation from the Sun is absorbed.
The top of the mesosphere, ranges from 50 to 85 km, wherein most meteors burn up. The thermosphere extends from 85 km to the base of the exosphere at 690 km and contains the ionosphere, a region where the atmosphere is ionized by incoming solar radiation. The ionosphere increases in thickness and moves closer to the Earth during daylight and rises at night allowing certain frequencies of radio communication a greater range. The Karman line, located within the thermosphere at an altitude of 100 km, is commonly used to define the boundary between Earth's atmosphere and outer space.
The exosphere begins variously from about 690 to 1,000 km above the surface, where it interacts with the planet's magnetosphere to space. Each of the layers has a different lapse rate, defining the rate of change in temperature with height.
The UV atmospheric level in the heights of stratosphere, just above the troposphere, if we want to know anything about the global weather dynamics, the troposphere is its area and field of studies.
Oxygen discharge (spectrum) tube. The green color is similar to the color of an "aurora borealis"
Ozone layer in Stratosphere
Ozone or trioxygen is an inorganic molecule with the chemical formula 03. It is a pale blue gas with a distinctive pungent smell. It is an allotrope of oxygen that is much less stable than diatomic allotrope O2, breaking down in the lower atmosphere to normal dioxygen. Ozone is formed from dioxygen by the action of ultraviolet light and also atmospheric electrical discharges, and is present in low concentrations throughout the Earth's atmosphere (stratosphere).
Space Shuttle Endeavour appears to straddle the stratosphere and mesosphere in this photo. "The orange layer is the troposphere, where all of the weather and clouds which we typically watch and experience are generated and contained. This orange layer gives way to the whitish Stratosphere and then into the Mesosphere." (The shuttle is actually orbiting at more than 200 miles in altitude, far above this transition layer.)
Reference:
1. Stratosphere in wikipedia
2. Ozone in wikipedia
