Why is the atmosphere blue? It's purple!
Any child draws a picture of the sky blue in their first drawings. It would seem that it is, it is enough to look out the window in clear weather to be convinced of this. But, in fact, we see the atmosphere blue because of the peculiarities of vision and the optical laws of physics. If it weren't for them, the atmosphere would be purple.
When sunlight passes through gas and water vapor, it scatters. In doing so, short emissions, including the violet tone of the spectrum, are absorbed more strongly. Human eyes, on the other hand, are more sensitive to the blue hue, that is, they perceive it better than violet. As a result, when we look at the sky, it looks blue to us.
Oxygen content in the atmosphere of the Earth and other planets
Our atmosphere contains less than 21% oxygen by volume. Nitrogen, ≈78%, and oxygen make up the bulk of the atmosphere. The other gases make up only 1%. Few people know that the Earth has far from the highest oxygen content in its atmosphere. For example, Mercury has about 42% of this gas. However, you won't be able to breathe it, since the atmosphere on the planet is very rarefied.
In general, the density of Earth's atmosphere is the third among the celestial bodies of the solar system. More dense atmosphere on Titan, as well as on Venus, which ranks first in this indicator. The density here is so high that closer to the surface, it gradually becomes liquid and gradually turns into an ocean.
By the way, oxygen on Earth in such large quantities did not appear immediately. Scientists attribute the saturation of the atmosphere with oxygen to the slowing down of the Earth's rotation as a result of the appearance of the Moon.
Greenhouse gases in the atmosphere are necessary
We all know that greenhouse gases are excessively dangerous to the atmosphere - they cause global climate warming, as I said above. Scientists approach the issue of limiting greenhouse gases in the atmosphere in different ways. Some ideas seem fantastic. For example, I recently told you that scientists are working on "reviving" mammoths, which, according to their idea, should restore pastures in the Arctic.
However, it would also be uncomfortable on Earth without greenhouse gases at all. The fact is that they absorb solar energy and distribute it evenly over the Earth's surface. Without them, most of the globe would be too cold, while the equatorial zone would be unbearably hot. Thus, the atmosphere contains the ideal composition of gases for comfortable life, and changing it would have serious consequences.
Airplane footprints in the sky - where do they come from?
Have you ever wondered why there is a white "track" in the sky after a jet plane that looks beautiful against the blue sky? We've all watched it last a long time and then slowly dissipate. What we actually see in the sky is ice. It results from the cold atmosphere meeting the moist and hot exhaust of an airplane. The resulting water immediately turns into small crystals.
If the trail is poorly visible and dissipates quickly, it means that there is low humidity at the altitude where the airplane is flying. If the trace is clear and holds for a long time, correspondingly, there is high humidity in the air. This means that the weather may worsen in the near future, even thunderstorms are possible.
The troposphere is warmer than the stratosphere
Many people believe that the higher up, the lower the temperature in the atmosphere. However, this is not entirely true, the stratosphere, which is higher, is warmer than the troposphere. This is because it is where the ozone layer is located, which provides protection for Earth's inhabitants from deadly ultraviolet light.