Hot air or cold air is heavier, which is heavier cold air or hot air

Cold air is heavy. Cold air is heavy, and we learned in elementary school: "When the air is heated up, the cold air around it flows to replenish it, and the wind is formed."

So, why does air rise when heated? It turns out that this is because the air expands in volume when heated, and the specific gravity becomes lighter than the surrounding cold air, and the heavier cold air around it flows over and floats the lighter hot air to it, thus forming a wind.

The heat emitted by the conversion of hot air into cold air is equal to the amount of heat absorbed by the conversion of cold air into hot air. In the process of changing the temperature of the air, the total mass of air and heat in nature does not increase or decrease. However, the volumetric change that occurs in the air during this temperature change causes the air on the ground to flow – generating wind and an inexhaustible supply of wind energy.

Hot air balloons are the best proof of this.

Since: at constant pressure, for the presence of an ideal gas, PV=NRT

So, volume is directly proportional to temperature, and density is inversely proportional to temperature.

Because of thermal expansion and contraction, the cold air becomes hot air at the heated side, and the volume becomes larger, and the mass remains the same, so the density becomes smaller. Because the hot air is light, it will rise, and the cold air will fall and rise again after being heated, so that the temperature of the room will rise.

The cold air is heavier, and if you look closely, the cold air of the ice cream is coming downward, indicating that the cold air is heavier.

Cold air is heavy because of thermal expansion and contraction.

At the same volume, hot air will weigh less than cold air.

When the air expands when heated, the density decreases, and the same volume of cold air will be heavier than it. At different temperatures and pressures, the density of air is not the same, at one atmospheric pressure, under standard conditions, the density of air is about 20, and it is not the same volume of air can not be compared.

Atmospheric mass density depends on air temperature, air pressure and humidity, and is usually difficult to obtain directly, but is generally calculated and decreases exponentially with altitude. The density of the air around us is under standard conditions (0,101kpa) and the standard value of atmospheric density at sea level is .

Factors influencing air density

The density of air is mainly affected by two conditions: air pressure and air temperature. The atmosphere surrounds the surface of the earth, so the air pressure in the lower layers of the atmosphere is higher, and the higher the air pressure is, the lower the air pressure. If the air pressure is high, the air density is high, and when the air pressure is low, the air density is low.

Therefore, under normal circumstances, the air density is always highest close to the ground, and the air density decreases the higher the air is up.

The effect of temperature on air density is the opposite of air pressure. The higher the temperature, the more the volume of the air expands, and the density of the air decreases; The lower the temperature, the more the air shrinks, and the density of the air increases. In general, the closer you get to the ground, the higher the temperature (with the exception of the inversion layer).

According to the measured results, in most cases, the difference between temperature and air pressure is not too large, but the difference between air pressure and air pressure is significant, so the effect of air pressure on the vertical distribution of air density is much greater than that of air temperature, which makes the air density often smaller and smaller as it goes up (although the decrease is not static).

Due to thermal expansion and contraction, the heated gas expands and the density decreases.

So the hot air rises and the cold air falls.

Atmospheric convection. Atmosphericconvection A vertical upward motion of a mass of air in the atmosphere under the action of heat or power. Atmospheric convection can generate the exchange of heat, momentum and water vapor between the lower and upper layers of the atmosphere on the one hand, and the condensation of water vapor caused by convection on the other hand may produce precipitation.

Atmospheric convection under thermal action mainly refers to the upward movement formed under the action of net Archimedes buoyancy in an atmosphere where the density of a mass of air is less than that of the ambient air, so that its buoyancy is greater than that of gravity. Small, short-term, sudden, and cumulonimbus precipitation that is often seen in summer is often caused by atmospheric convection under the action of heat. Atmospheric convection under dynamic action mainly refers to the upward movement formed under the condition of horizontal convergence of airflow or the presence of topography.

Precipitation over a wide area in the atmosphere is often caused by the convergence and uplift of fronts and associated airflows, while precipitation in fixed areas near mountain ranges is often caused by topographic forced uplift. Some special topography (e.g., flare-shaped topography) creates atmospheric convection that has both the effect of topographic uplift and the effect of terrain in making the airflow converge horizontally.

On the one hand, the thermal and dynamic effects can form atmospheric convection, and on the other hand, atmospheric convection can affect the thermal and dynamic structure of the atmosphere, which is the feedback effect of atmospheric convection. This feedback is particularly important in tropical regions where the atmosphere is located, and the condensation heating of water vapor formed by atmospheric convection is often an important energy source for large-scale atmospheric movement in this region.

The principle of thermal expansion and cold contraction. Hot air is larger than cold air by the same weight, so hot air with the same volume is lighter than cold air.

Because the volume of air expands when heated, hot air is lighter than cold air in the same space.

Analysis: Air Affected.

Thermal expansion, in proportion to the same volume of cold air, becomes less dense and the weight will be lighter. The density of air varies depending on the temperature and pressure. At one atmosphere, under standard conditions (0, 1 atm), the air density is about.

20 o'clock, take.

Therefore, due to the influence of temperature, the air density of hot air is less than that of cold air, and the weight of hot air will be lighter for the same volume.

Hot air of the same volume is lighter than cold air.

The air expands by heating, compared with the same volume of cold air, the density becomes smaller, the weight will be lighter, the air density is not the same at different temperatures and pressures, at one atmosphere, under standard conditions (0, 1 standard atmosphere (1atm)) the air density is. 20 o'clock, take.

Atmospheric mass density, which depends on air temperature, air pressure and humidity, is usually not measured directly, but is calculated and decreases exponentially with altitude. The density of the air around us is under standard conditions (0 (273k), 101kpa). The standard value of atmospheric density at sea level is kilograms per cubic meter.

Air Principle:

Air is a mixture of a variety of gases, its constant components are oxygen, nitrogen and argon, neon, helium, krypton, xenon and other noble gases, variable components are carbon dioxide and water vapor, their content in the air will vary slightly in a small range with the location and temperature of the earth, as for the indefinite components of the air, it varies with different regions.

Experiments have shown that the percentage of constant components in the air is almost constant up to 100 km above the ground. In terms of volume content, oxygen accounts for about about it, nitrogen about about it, and argon about about it.

The reason why the main components of nitrogen and oxygen in the air are relatively constant is the result of mutual compensation for various changes in nature, the respiration of animals and plants, the combustion of substances, the decay of animals and plants, and the corrosion of steel all need to consume a large amount of oxygen, but green plants also need to photosynthesize in the sun, that is, inhale carbon dioxide in the air and release oxygen at the same time.

Experiments have shown that the total amount of oxygen released by the plant is about 20 times more than the amount of oxygen it needs to breathe, which is the reason why the amount of oxygen remains relatively balanced.

The reasons why cold air is heavier than hot air are as follows:

1.The density of cold air molecules is greater: due to the lower temperature, the spacing between the molecules of cold air is lesser and hence the density is greater, comparatively, in contrast, the spacing between the molecules of hot air is greater and hence the density is less.

2.The molecular structure of cold air is tighter: cold air molecules move more slowly at low temperatures, so the interaction between the molecules is stronger and the structure is tighter, making the cold air denser.

3.The molecular mass of cold air is greater: Since the spacing between the molecules of cold air is smaller, the interaction forces between the molecules are stronger, making the average mass of the molecules of cold air greater and therefore denser.

In summary, the reason why cold air is heavier than hot air is mainly due to the smaller spacing of molecules, tighter molecular structure, and greater molecular mass due to lower temperature.

It has to do with density. Cold air is dense. The molecular motion between the cold air decreases, the kinetic energy decreases, and the inertial acceleration decreases, so the molecular spacing also decreases, in other words, the more molecules can be accommodated per unit space, the density will be larger, and the mass will also become larger.

In other words, cold air, when the air is cold, shrinks in volume, so it becomes denser.

About the hot acres of coarse air rises Leng Xun town air falls also.

According to the principle of thermal expansion and contraction, hot air is larger than cold air with the same mass, so hot air with the same volume is lighter than cold air.

The principle of thermal expansion and contraction usually refers to the fact that when the external pressure remains unchanged, the volume of most substances increases when the temperature increases; A phenomenon in which its volume shrinks when the temperature decreases. Objects expand when heated and contract when cold. This is due to the fact that the motion of the particles in the object changes with the temperature, and when the temperature rises, the vibration amplitude of the particles increases, causing the object to expand. However, when the temperature drops, the vibration amplitude of the particles decreases, causing the object to contract.

Which is heavier, cold air or hot air

1.Hot air is lighter than cold air. The cold air is heavy, the air is heated and rises, and the surrounding cold air is replenished, and the wind is formed. Air is a mixture of various gases in the Earth's atmosphere. It is mainly composed of 78% nitrogen, 21% oxygen, 1% noble gases and impurities.

2.The composition of the air is not fixed. As the altitude and pressure change, so does the composition of the air.

But for a long time, people thought that air was a single substance, until the French scientist Lavoisier first concluded through experiments that air is composed of oxygen and nitrogen. At the end of the 19th century, scientists found that the air contains rare gases such as helium, argon, xenon, and neon through a large number of experiments. In its natural state, air is tasteless and tasteless.

Oxygen in the air is necessary for all aerobic organisms. All animals need to breathe oxygen. Plants use carbon dioxide from the air for photosynthesis.

Carbon dioxide is the only carbon in almost all plants**.