It s cold before frost and cold after snow. Do you think this statement makes sense? Why? Please use

1.Cold before frost: Frost is an ice crystal formed by the condensation of water vapor in the air on the ground at low temperatures. For water vapor to condense out of the air, the temperature must be very low, at least below 0 degrees Celsius, so the temperature should be very low before the frost sets.

Another reason is that because the time of frosting is about 1-4 o'clock in the morning, the human body's body and psychology are at a low ebb, and the food on the eve of the human body has been almost consumed.

And at this time, the water vapor of the air is saturated, and the humid and cold environment will make people feel colder.

The process of water vapor condensation is exothermic, that is, a large amount of heat is released in this process, so that the cold of the air will be relieved, which may be the reason why it is not too cold after frost.

2.Cold after snow: Snow solidified from a liquid state to a solid state is exothermic, and because it is cloudy when it snows, clouds can reflect a lot of long-wave radiation from the ground, and even visible light, so it can have a thermal insulation effect, so it is not too cold before the snow, but the temperature has dropped to about zero degrees.

After snowfall, because the ground is controlled by a cold air mass, the weather is clear, and the ground often has snow, during the day, the snow can reflect the heat radiation from the sun, and the snow melting is a process of transformation from solid to liquid, which is to absorb a lot of heat.

At night, because the weather is fine, the temperature is relatively low, there is very little water vapor in the air (water vapor can absorb more long-wave radiation), and there is no cloud reflection in the sky, and the long-wave radiation from the ground can pass through the atmosphere unimpeded and be lost to outer space, so the temperature will drop sharply.

In another case, the snow absorbs the remaining heat from the ground and lowers the temperature to around zero, at which point the cold air from the north continues to advance, causing the air temperature to drop even further. Therefore, it is said: cold after snow.

If the days after the snow are still cloudy and there is no follow-up strong cold air, the days are not so cold.

It makes sense that when the frost is formed, it is the condensation of water vapor in the air, and the heat release will increase the temperature, so it will be a little colder before the frost falls.

When the snow melts, it absorbs heat and lowers the temperature, so the snow gets a little colder.

The physical causes of cold before frost and cold after snow are the condensation and melting of vertical grinding, which require heat absorption.

Cold before frost: Frost is water vapor in the air in early winter.

At night, when strong cold air condenses into Xiaoice crystals, which are formed on the ground, the temperature before the frost must be low enough (below 0) to form frost fibers, so it feels cold.

Cold after snow: Snow is a high altitude of water vapor condensed into Xiaoice crystals after falling to the ground, after snow, snow begins to melt, melting is the process of converting solid to liquid state, to absorb heat.

Substance dissolution, endothermic and exothermic formula.

Gases become other exothermic and solids become other endothermics. It becomes endothermic as a gas and exothermic as a solid. Chemical reaction.

A reaction in which the total energy of the reactants is greater than the total energy of the products is called an exothermic reaction.

An endothermic reaction is a chemical reaction that absorbs heat in the process. The memorization formula is that the gas bucket becomes other exothermic and the solid becomes other endothermic. It becomes endothermic as a gas and exothermic as a solid.

Physical causes of cold before frost and cold after snow: Frost is in the air in early winterWater vaporAt night, when strong cold air condenses into Xiaoice crystals, it is formed on the ground, and the temperature before the frost must be low enough (below 0) to form frost, so it feels cold.

Snow is the high altitude water vapor condensed into Xiaoice crystals and then descended to the ground, after the snow, the snow began to melt, melting is the process of transforming the solid state into a liquid state, to absorb heat. Therefore, when the snow melts, the temperature of the air above the ground decreases, and people have the feeling of chilling after the snow.

Cold before frost, cold after snow" describes the change of state of matter.

Generally speaking, there are three states of matter: solid, liquid and gaseous, and the corresponding substances are called gases, liquids, and solids, and the three phases can be converted into each other.

Distinguish between frost and frost

There is a difference between frost clusters and frosts. Frost refers to white solid condensate, and frost refers to the low temperature of the ground and plant surfaces during the growing season when the temperature of the ground and plant surfaces drops enough to cause injury or death to the crop. When there is frost, crops are not necessarily affected by frost.

There can be frost when there is frost (hoarfrost), or there can be no frost at the end (black frost).

Therefore, it is frost and not frost that we want to prevent. Frosts, especially early frosts (or early frosts) and late frosts (or final frosts), are more threatening to crops and should be paid attention to, and preventive measures such as fumigation, watering, and mulching should be taken.

Frost is due to the condensation of water vapor in the air to form a line of high, the condensation process of water vapor to release heat to the air, if the air temperature is high, the water vapor in the air can not be heated, only when the air temperature suddenly decreases can the water vapor be heated, therefore, the air temperature before frost must be very low, that is, people call "cold before frost";

When snow falls, the snow melts, and the snow absorbs heat from the surrounding air during the melting process, so the temperature of the air is lowered and we feel "cold after snow".

It makes sense, because it absorbs heat before frost and exothermic after frost; Exsitates heat before snow and absorbs heat after snowfall. The liquid becomes solid and exothermic, and the solid becomes liquid and endothermic; Absorb heat and cold, release heat and warm.

That's right. Trust me

Frost is formed by the condensation of water vapor.

If the temperature is not cold enough, it will turn into dew, not frost.

When the temperature is cold, the frost can form, so it is cold before the frost.

The snow has to sublimate, it has to absorb heat, and the surrounding temperature is sucked over (==) so the temperature is cold.

Eight after physics class www ask t

Because the formation of frost is formed by water vapor heat absorption and condensation, since it is cold, the temperature must be low, and after the snow, the snow will melt and sublimate, and it will absorb heat to reduce the temperature of the surrounding air, so it is cold before the frost and cold after the snow.

The big brother on the first floor: I copied it somewhere else.

Is the condensation on the third floor good or not?