Science Popularization｜What do you know about this interesting scientific knowledge?

What happened to thunder?

It is a natural phenomenon when negative and positive electricity meet together. When it rains, some clouds in sky are positively charged and some are negatively charged. When two kinds of clouds meet together, they discharge and emit very bright lightning. At same time, they radiate a lot of heat. , due to which surrounding air quickly heats up, expands and makes a loud noise - thunder.

Why is sky red at night?

Morning and evening, before and after sunrise and sunset, colorful clouds often appear in sky. The formation of morning glow and sunset glow is due to scattering effect of air on light. When sunlight enters atmosphere, it collides with atmospheric molecules and particles suspended in atmosphere and is scattered. These atmospheric molecules and particles do not themselves emit light, but because they scatter sunlight, each atmospheric molecule forms a diffuse source of light. According to Rayleigh's law of scattering, violet, blue and blue light with shorter wavelengths in solar spectrum are most easily scattered, while red, orange and yellow with longer wavelengths have a high transmittance. Therefore, we see that clear sky is always blue, and light above horizon is only yellow, orange and red light with a longer wavelength. After these rays are scattered by impurities, such as air molecules and water vapor, sky there takes on bright colors.

Mirror out of shape?

The farther a person is from mirror, more he loses his shape. Since image in a mirror is formed by reflection from silver plated surface behind mirror, uneven silver plated surface or uneven glass thickness causes aliasing. For a non-standard mirror, farther a person is from mirror, greater deviation from normal position of reflected light on silver-plated surface, due to principle of light amplification, and greater deviation from normal position. -The shape of mirror will be.

How high is blue sky?

The "blue sky" is actually Earth's atmosphere. The atmosphere surrounds earth's air, which is divided into 5 layers according to air density, and has a total thickness of 2000-3000 kilometers. But most of air is concentrated from ground below 15 kilometers, and higher you go, thinner air becomes. What a dense atmosphere, how high must be blue sky.

Why do sunflowers always face sun?

Sunflower stems contain wonderful auxin. This auxin is very sensitive to light. When it meets light, it moves to backlight side, and at same time stimulates cells on backlight side to multiply rapidly, so backlight side grows faster than light side, which causes sunflower to produce phototropic bending.