When we look at the albedo, which is the Earth’s reflectance of sunlight, we find that the Earth has something like a magnetic or atmospheric barrier, and that these barriers also have something like windows through which energy can pass in and out at a moderate rate. In particular, it seems that thermal energy and magnetic energy often come in on electromagnetic waves from outside the Earth, and the ranges that allow electromagnetic waves of specific wavelengths to pass through are called windows, and there seem to be geomagnetic windows, ionospheric windows, atmospheric windows, and so on.
Geomagnetic window
The magnetosphere, generated by the Earth’s geomagnetic field, seems to act as a barrier against the solar wind, but in areas such as the Antarctic and Arctic, the magnetic field lines are nearly vertical, making it easy for particles to enter. In addition, when solar wind plasma flows in from areas of the Earth’s magnetic field where the density is low, an area called the plasma sheet is created, and the plasma from this area flows into the polar regions, causing phenomena such as the aurora.
Window to the ionosphere
The Earth’s ionosphere, which is ionized by ultraviolet rays and X-rays, seems to act like a barrier that reflects electromagnetic waves of many wavelengths, mainly reflecting low frequencies up to 30 MHz, absorbing some mid-frequency waves up to 300 MHz, and allowing high frequencies above 300 MHz to pass through. The size of the area seems to change depending on the amount of ultraviolet rays, and is linked to the approximately 11-year cycle of solar activity.
atmospheric window
The Earth’s atmosphere, which contains gases such as water vapor, carbon dioxide, and ozone, seems to act as a barrier that absorbs part of the electromagnetic waves, but it also has windows that allow electromagnetic waves such as visible light and infrared rays to pass through. Nitrogen absorbs electromagnetic waves below 0.1 μm, oxygen absorbs ultraviolet rays from 0.1 to 0.2 μm, and ozone absorbs ultraviolet rays from 0.2 to 0.3 μm, which are too strong for living organisms. In addition, methane, carbon dioxide, and water vapor absorb some infrared rays to keep the Earth’s surface warm.
Visible light is able to reach the Earth’s surface because it is not absorbed by these elements, and infrared light, which has a frequency band that is not absorbed, allows the heat that has accumulated on the Earth’s surface to be released into space.
The Window of the Earth is amazing
It’s amazing how the Earth’s structure can function both as a barrier and as a window for passage in and out. Without a barrier, creatures on the surface of the Earth would be exposed to strong electromagnetic waves, and without windows, light would not pass through and heat would not escape. It is this exquisite combination of opposing roles that allows creatures on Earth to survive. The composition of the atmosphere is amazing. The windows of the Earth are amazing.
