How Fast Does Water Evaporate?

The water takes 1.2 hours to fully evaporate. 1 hour for evaporation seems pretty fast, but I did use a large convection coefficient from the beginning. 0.1 ounces of evaporation occurs every 1.2hrs and we will now multiply that by 8ounces which is a cup this would equal (9.6) 9days 6hrs… so Its 8oz.

Evaporation happens when a liquid substance becomes a gas. When water is heated, it evaporates. The molecules move and vibrate so quickly that they escape into the atmosphere as molecules of water vapor.

Evaporation is a very important part of the water cycle. Heat from the sun, or solar energy, powers the evaporation process. It soaks up moisture from soil in a garden, as well as the biggest oceans and lakes. The water level will decrease as it is exposed to the heat of the sun.

Although the level of a lake, pool, or glass of water will decrease due to evaporation, the escaped water molecules don’t disappear. They stay in the atmosphere, affecting humidity, or the amount of moisture in the air. Areas with high temperatures and large bodies of water, such as tropical islands and swamps, are usually very humid for this reason. Water is evaporating, but staying in the air as a vapor.

How Fast Does Water Evaporate

What Are the Factors Affecting Water Evaporation?

The factors that affect the rate of evaporation of liquids are temperature, surface area, wind speed, and humidity.

Purity of the Water

Pure or distilled water evaporates faster than saltwater and other types of impure water. The evaporation rate for fresh effluent was 8.3–10.7% higher than the clear water evaporation rate and concluded that dark-colored wastewater absorbs more solar radiation, enhancing its evaporation compared to clear water.

Also, they pointed out that wastewater evaporation may be enhanced due to increasing vapor pressure of the solution because of the high ammonia concentrations in wastewater.

The vapor pressure of sea water which has 35,000 ppm dissolved salts is about 2 per cent less than that of pure water at the same temperature. It is seen that the evaporation rate decreases with increase in specific gravity of the solutions.

Surface Area of the Water

Molecules contained in a liquid evaporate from the surface area. This means that the larger the surface area, the faster the rate of evaporation. It is because, the larger the surface area that is exposed to air, the more molecules will escape into the air.

The greater the surface area of the water, the faster it evaporates. You can see this by putting water into two different containers. Use one that has a diameter of a 3 or 4 inches, such as a glass, and another that has a diameter of 8 to 10 inches, such as a bowl.

Put 2oz of water into a measuring jug then transfer it to the glass. Do the same for the bowl and then place the containers next to each other. This means all the other factors that affect the rate of evaporation are identical.

Leave the containers for one hour. Pour the water from each container into the measuring jug and write down how much water is left. The amount of water left in the bowl is much less than is left in the glass, due to the difference in surface area. If the surface area is so large that the water is only one molecule deep, it evaporates almost immediately.

Temperature of the Water

Evaporation happens in room-temperature water and even in cold water because at those temperatures, a portion of water molecules have enough energy to break away from other water molecules (evaporate).

When a faster-moving molecule is at the surface, it can break away from other molecules even though most of the other molecules are moving more slowly. On cold days, water evaporates, but it evaporates more slowly than it would on a warmer day

Although water can evaporate at low temperatures, the rate of evaporation increases as the temperature increases. This makes sense because at higher temperatures, more molecules are moving faster; therefore, it is more likely for a molecule to have enough energy to break away from the liquid to become a gas.

Relative Humidity of the Air

The amount of water in the air as a fraction of the total amount the air can hold when it is saturated is called relative humidity. Evaporation increases with a decrease in humidity. The air around can only hold a certain amount of vapor at a certain time and a certain temperature.

If the temperature increases and the wind speed and humidity stay constant, then the rate of evaporation will increase since warmer air can hold more water vapor than colder air. For example, if you live in the desert, the water evaporates much faster in an area with no other water than it does if the water is next to a lake.

There are too many variables as basic data to provide an exhaustive answer to the question, how fast does water evaporate? Also, each of the above variables work together to affect the rate of evaporation.

For example, when temperature and humidity are steady and wind speed increases, the rate of evaporation also increases. When temperature and wind speed are steady, but humidity increases, the rate of evaporation decreases.