The formation of clouds is due to the rise of humid air. In the process of rising, because the external air pressure decreases with the height, its volume gradually expands, and it consumes its own heat in the process of expansion. In this way, the air rises and cools, forming clouds.

2, the sun

Located in the center of the solar system, the sun is almost an ideal sphere where hot plasma and magnetic field are intertwined. The diameter of the sun is about1392000 (1.392×10? ) kilometers, equivalent to 109 times the diameter of the earth; Its volume is about 6.5438+0.3 million times that of the earth.

3. Moon

The moon, known in ancient times as Taiyin, Xuantu, Chanjuan and Pan Yu, is the satellite of the earth and the fifth largest satellite in the solar system.

4. Stars

The energy activity inside the star makes the shape of the star irregular. Stars can be roughly divided into planets, stars, comets, white dwarfs and so on. The brightness of a star is usually expressed in magnitude. The brighter the star, the smaller the magnitude.

5. Rainbow

When the sun shines on the water droplets in mid-air, the light is refracted and reflected, forming an arched colorful spectrum in the sky, which is red, orange, yellow, green, blue, indigo and purple in turn from the outer ring to the inner ring. Seven colors. In fact, rainbows have countless colors. For example, there are many subtle differences between red and orange, but for simplicity, only seven colors are used as the differences.

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