In hot weather, the ice cream just taken out of the refrigerator will give off white gas. What's going on here?
The freezing temperature is generally -20 degrees Celsius, and the temperature in the air is much higher than this in summer. When the ice cream was just taken out of the refrigerator, the environment of the ice cream had changed, from -20 degrees Celsius to more than 30 degrees Celsius. If ice cream wants to melt, it needs to absorb heat. The air next to the ice cream dissipates heat, the temperature drops, and there is some moisture in the air. Then when it cools to a certain extent, a part of the water vapor in the air will condense out and be suspended in the air.
"White gas"?
1. Meaning: "White gas" is not water vapor, because water vapor is a colorless and transparent gas and is invisible. When water vapor meets air with low outside temperature, it will give off heat and liquefy to form small water droplets, which are suspended in the air, which is what we see as "white gas". For example, in winter, the "white gas" exhaled in the mouth; The "white gas" sprayed from the spout when boiling water; In summer, we see the "white gas" emitted by popsicles; The "white gas" emitted when the refrigerator door is opened; White exhaust gas from airplanes. ?
2. Classification: The phenomenon of "white gas" can be divided into two categories, one is that cold objects emit "white gas"; The other is that hot objects emit "white gas". Although they are all small water droplets liquefied by water vapor when it is cold, the source of water vapor is different.
For example, the "white gas" of popsicles is formed by the liquefaction of water vapor in the air around popsicles (from the outside of popsicles); When boiling water, the "white gas" emitted from the spout is caused by the liquefaction of water vapor (from inside the kettle) when it meets the cold air near the spout. Remember: the characteristic of * * is that water vapor should be cold.