why do we have water vapour in the air if water boils at 100 degrees?

Answer 1

You have to distinguish between evaporative and boiling processes...at 100C, water boils. But between 0 and 100C, water evaporates (the higher the temperature, the greater the evaporation).

Because it evaporates (from the ocean water, lakes, rivers, etc.) we have water vapour (humidity) in the air.

Hope this helps :-)

Answer 2

Water is always evaporating at a low rate and thus there is always some water vapor in the air. Water boils when the rate of evaporation is high enough that the evaporating water creates as much pressure from within the water as the atmosphere does from outside the water. In this situation, the water vapor forms bubbles rapidly and the water boils.
This is also why water boils at a lower temperature (and cooking takes longer) at higher altitudes where the atmospheric pressure is lower.

Answer 3

Water is made up of molecules. These molecules are moving around and bouncing off each other. The molecules possess an average energy that increases as temperature increases.

As the molecules move around and bounce off each other, they transfer energy from molecule to molecule. Each molecule has a different amount of energy in some kind of statistical distribution. The molecules at the very high end of the distribution have enough energy to break free of the liquid phase if they are near the surface of the water. This means that water is evaporating all the time, even at low temperatures. Furthermore, the rate of evaporation increases with temperature.

However, water molecules in the air fly around and bump into other gases, exchanging energy, and some will collide with the liquid water, lose energy to the water, and enter the liquid phase. The rate of condensation increases when there are more water molecules in the gas phase.

Thus water molecules are being constantly exchanged between the liquid and gaseous states. At equilibrium, the rate of evaporation equals the rate of condensation, and there is no net change of the amount of liquid water present. Thus there is always at least a little bit of water in the air.

The amount of water that the air can hold at equilibrium can be measured in many ways, such as humidity, relative humidity, and the vapor pressure.

The amount of water able to be held in the air at equilibrium increases with temperature. In particular, at the boiling point of water, 100 degrees, the vapor pressure rises to 1 atmosphere (atmospheric pressure). This means that liquid water will (on average) move from liquid to gas phases until the whole atmosphere is full of water. This means that there is "no limit" to the amount of water that can be held in the gas phase. On the other hand, when humid air is cooled, (like your breath in the winter time) the amount of water that can be held in the gas phase decreases below the current amount held, and water will leave the gas phase forming droplets and you can see your breath.

Answer 4

Actually, water boils at 100 degrees celcius, but it also gets evaporated. In evaporation, only the high energy molecules leave the surface of water due to higher molecular activity and this can take place at the room temperature too! One example is the earthpot, in which the water inside it, gets cooled due to the evaporation of water from its pores and only less energy molecules leave making water cool.

Answer 5

Hi. At 1 atmosphere water does boil at 100 Deg C. But it evaporates at most normal temperatures.

Answer 6

Vapor rigidity and boiling factor have an intimate dating. The boiling factor is the temperature at which the vapor rigidity of the liquid equals the exterior rigidity. to illustrate, simply by fact the air rigidity is decrease in a city far above sea point inclusive of Denver, the boiling factor of water is under in a sea point city inclusive of long island. the main uncomplicated unit for vapor rigidity is the torr. a million torr = a million mm Hg (one millimeter of mercury). maximum components have very low vapor pressures. to illustrate, water has a vapor rigidity of roughly 15 torr at room temperature. yet undergo in techniques that vapor pressures develop with temperature; water could have a vapor rigidity of 760 torr = a million atm at its boiling factor of a hundred oC (212 oF). frequently, the better the vapor rigidity of a fabrics at a given temperature, the decrease the boiling factor. In different words, compounds with intense vapor pressures are risky, forming a intense concentration of vapor above the liquid; this could in specific situations pose a hearth probability.

Answer 7

Water can evaporate from the surface at any temperature. Factors effecting evaporation include surface area, wid, and temperature. Water can even sublime(change directly from a solid to a gas).

Answer 8

Water at 100 degrees is known as STEAM, not water vapour.

Answer 9

as long as the temp is plus 0 c
water will evaporate.
very slowly of course,
but as the temp rises evaporation will happen more quickly.
at 147 degress F you will be able to see the evaporation process