What are the conditions for snowfall? How many degrees does the snowfall usually reach?

After a night of winter, it has begun to snow in some places. What conditions do you usually meet when it snows? When will the room temperature reach the temperature of snowfall?

What are the conditions for snowfall?

1, water vapor saturation

The maximum amount of water vapor that air can hold at a certain temperature is called saturated water vapor. The temperature at which air reaches saturation is called dew point. When saturated air is cooled to a temperature below the dew point, the excess water vapor in the air becomes water droplets or ice crystals. Because the saturated water vapor content of ice surface is lower than that of water surface, the water vapor saturation required for the growth of ice crystals is lower than that of water droplets.

That is to say, water droplets can grow only when the relative humidity (relative humidity refers to the ratio of the actual vapor pressure in air to the saturated vapor pressure of air at the same temperature) is not less than 100%; As for ice crystals, they tend to grow when the relative humidity is less than 100%.

For example, when the temperature is -20℃ and the relative humidity is only 80%, ice crystals can grow. The lower the temperature, the less humidity is needed for the growth of ice crystals. Therefore, in the high-altitude and low-temperature environment, ice crystals are more likely to be produced than water droplets.

There are condensation nuclei in the air.

Without condensation nuclei, it is difficult to see rain and snow on the earth. Condensation nuclei are tiny solid particles suspended in the air. The ideal condensation nuclei are those particles that absorb the most water. Such as sea salt, sulfuric acid, nitrogen and other chemicals. So sometimes there are clouds in the sky, but there is no snow. In this case, people often use artificial snowfall.

How many degrees does the snowfall usually reach?

Snowfall requires not only water vapor temperature below 3 degrees Celsius, but also other conditions to form.

Water vapor in the atmosphere condenses directly or water droplets condense directly, which is snow. It can also be said that it snows when the temperature in the cloud is too low and small water droplets form ice crystals and fall to the ground or snow. Ice absorbs heat when it melts, so the ground temperature will be lower than when it snows.

Many snowy residents in Shaanxi wear cotton-padded clothes in advance.

10 June10, Binzhou and Baoji in Xianyang, Shaanxi ushered in the first snow in the second half of 200210.

The snow in Shaanxi this year is earlier than in previous years, about one or two months, and the temperature is very low. Many people have put on their cotton-padded jackets in advance.

Affected by snowfall, Taibai Mountain and red river valley Scenic Area have been temporarily closed since the 9th, and the opening hours will be announced separately.

According to the weather forecast, in the coming week, Baoji will be mainly cloudy, with light rain in some areas, sleet or light snow in the northern and southern mountainous areas, and continuous rainy weather in Xianyang.

Previously, on September 28th, the first snow of this year fell in Daxing 'anling and Huzhong Town of Heilongjiang Province.

What is the physical phenomenon of snowfall?

Snow is a phenomenon.

Formation of snow: In winter, the air is cold, and the water vapor cools sharply, which directly condenses into hexagonal small ice crystals-snowflakes. When snowflakes fall, they combine with each other and change from small to large into snowflakes or large snowflakes. At this time, it snowed heavily.