Rainbow only appears after summer rain?

After the showers in the summer, a sky strip of rainbows with seven colors: red, orange, yellow, green, blue, violet induced by sunlight is refracted from the sky. droplets.

In the summer, the time of the showers is not very long, in addition the range is not wide, so after the rain the sunlight will appear immediately. At this time in the air still filled with water particles, or sometimes still shady rain. When sunlight is refracted and reflected by water particles, the seven-colored rainbow will appear in the sky.

In winter, the weather is cold and the air is very dry, rarely rains occur, so the showers are less so they are not eligible to create a rainbow.

Why does the rainbow have an arc?

According to the laws of physics, a light ray passing through a drop of water will be diverted by the refractive nature of the water, then reflected back by the surface in the water droplet and then refracted again when it comes out. Between the incoming ray and the ray coming out of the drop formed an angle of about 42 degrees. Sunlight consists of rays of different wavelengths and they will be separated when passing through water droplets. The degree of refraction of these rays is slightly different. Purple rays come out of the water drop at an angle of about 40 degrees while the red ray comes out at about 42 degrees.

In order to see the rainbow, the light reflected from the water droplet must reach the observer's eye. The eyes cannot receive all the rays that reflect from a drop of water, but can see blue rays from these few drops, red rays from several other droplets .

Water droplets with red rays reflecting on the observer's eye are droplets that lie on a cone whose peak is the observed position, the axis being the line that passes through the eye and is parallel to the sun, the slope of The cone is the angle at which this ray reflects off the droplets (42 degrees). Same with other colors. Thus, the observer will see the colored, out-of-the-inside colored rings (reflections from large to small) as follows: red, orange, yellow, green, blue, indigo if standing on an airplane or at a certain height.

Read more: "Discovering the origin of the rainbow"