How are clouds, rain, snow, fog, frost and dew formed respectively?

1, cloud

Cloud is a visible polymer floating in the air, which is condensed by small water droplets or small ice crystals liquefied by water vapor in the atmosphere when it is cold.

Clouds are the tangible result of the huge water cycle on the earth. The sun shines on the surface of the earth, and water evaporates to form water vapor. Once the water vapor is supersaturated, water molecules will gather around the dust (condensation nucleus) in the air, and the generated water droplets or ice crystals will scatter sunlight in all directions, thus creating the appearance of clouds. Moreover, clouds can form various shapes, and they are divided into many kinds because of their different heights and shapes in the sky.

Step 2 rain

Rain is a natural precipitation phenomenon, which is caused by the disturbance of atmospheric circulation. It is an indispensable part of the earth's water cycle and the only way for almost all terrestrial plants far away from rivers to replenish fresh water. Raindrops fall from the sky, big and small, fast and slow. The water on the earth's surface evaporates and rises, and it cools to form rain. Rainwater is the most important fresh water resource in human life.

3. Snow

Snow is a natural phenomenon that water falls after condensation in the air, or refers to falling snow; Snow is the solid form of water. Snowfall only occurs under the influence of very cold temperatures and extratropical cyclones, so the probability of snowfall in subtropical and tropical areas is relatively small.

4. Fog

When the relative humidity reaches 100%, the water vapor in the air will condense into fine water droplets suspended in the air, which will reduce the visibility on the ground. This weather phenomenon is called fog.

5. Frost

Frost is made up of ice crystals, similar to dew. When the relative humidity in the air reaches 100%, water is separated from the air. The only difference between them is that the dew point (the temperature at which water vapor liquefies into dew) is higher than the freezing point, while the frost point (the temperature at which water vapor condenses into frost) is lower than the freezing point, so frost will only appear when the near-surface temperature is lower than 0℃.

6. Dew

Dew refers to liquid water in which water vapor in the air condenses on ground objects. In the evening or at night, due to radiation cooling, the air layer near the surface also cools down. When the temperature drops below the dew point, that is, the water vapor content in the air is supersaturated, there will be water vapor condensation on the ground or the surface of the object. If the dew point temperature is above 0℃, tiny water drops will appear on the ground or ground objects, which is called dew.