The chromosphere is a narrow layer above the photosphere that raises in temperature with height. Normally, it can't be seen by the naked eye because the light from the photosphere of the Sun overpowers it. However, during a solar eclipse when this light is blocked out, it appears as a narrow, red ring around the Sun, with an irregular outer edge. The red from the chromosphere is also visible in prominences when they project from the Sun.
The edge of the chromosphere is made up of spicules. These are narrow columns of materials that ascend into the corona and last about 15 minutes. They are smaller eruptions, but eject material into the corona at high speeds. A lot of other solar events take place within the chromosphere also, such as solar flares and prominences.
One of the features of the chromosphere is the chromospheric network. It outlines the supergranules (see the photosphere section for an explanation of those)and is present there because of the magnetic field bunches in the supergranules. The network makes a web pattern of magnetic field lines on the Sun.
This is an image of the chromosphere. You can see the chromospheric network and the reddish light it casts.
One of the interesting things about the chromosphere is the way in which its temperature rises with height. One would expect that the temperature would decrease as the radiation coming from the photosphere moves up and more energy leaks out into space. This means there must be some other form of energy present that has nothing to do with the radiation coming from below the chromosphere. Scientists believe that this source of heating deals with wave motions, specifically magnetohydrodynamic waves. They are created when a magnetic field line is displaced. When the line tries to go back to its original shape, it begins to oscillate. This oscillating creates the waves that give up energy as they move through plasma, and causes the strange rise of temperature in the chromosphere.
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