Differences Between Evaporation and Transpiration

Evaporation and transpiration are both natural processes that help vapour formation through the loss of water. However, since they perform a similar function, it is often difficult to distinguish between evaporation and transpiration. Nevertheless, there are a lot of differences between these two processes.

The differences between evaporation and transpiration is discussed below - 


Evaporation 

Most of us are familiar with the concept of evaporation, whereby water is converted from its liquid state to a gaseous state. Evaporation usually takes place when solar energy heats water on surface water bodies like oceans, rivers and ponds.

Aside from water bodies, this process can also occur on other surfaces containing moisture such as soil and trees. 

Evaporation is a continuous process; however, the rate of evaporation at a given time can vary based on several factors. These factors are as follows – 

  1. Temperature – High-temperature results in increasing rate of evaporation and vice versa.

  2. Humidity – High level of humidity means that the atmosphere already contains a significant amount of water droplets. Therefore, the rate of evaporation will be low.

  3. The Surface Area of Water – The surface area of water is directly proportional to the rate of evaporation. 

  4. Wind – Wind help in evaporation by carrying away water vapour, which helps in the formation of more water vapour. Hence, wind speed also affects the rate of evaporation.


Transpiration 

The process through which plants absorb through their roots and then lose the excess water via stomata is known as transpiration. 

This process is similar to perspiration in human beings, preventing plant tissues from overheating when the temperature is high. Along with water, plants also gather essential nutrients from the soil. These nutrients are then transported to different parts of a plant such as stems and leaves through transpiration.

Some External Factors Which Affect the Process of Transpiration Include – 

  1. Temperature – When the temperature is high, plants transpire more as water on the surface of leaves starts evaporating more quickly with increasing temperature.

  2. Light – The stomata or tiny pores present in leaves detect presence and absence of light. The stomata open up widely when there is enough light, which facilitates both transpiration and photosynthesis. 

  3. Water Content in Soil – this is one of the most critical factors that affect transpiration in plants. A plant loses a large amount of water during transpiration. They make up for the loss of water by drawing water from the soil. Thus, if the soil does not contain adequate water, the stomata will close to preserve water leading to less photosynthesis.

The diagram below shows transpiration in plants – 

(image will be uploaded soon)


The main differences between evaporation and transpiration have been illustrated in the table below

Difference Between Transpiration and Evaporation

Evaporation 

Transpiration 

This is a physical process whereby liquid water changes to form water vapour.

This is a physiological process through which plants dispose of water.

Presence of water is required for this process

Living cells and tissues are required to carry out this process.

Evaporation can take place during both day and night

This process happens only during daytime

It is a fast process.

Compared to evaporation, this is a slow process

This process facilitates cloud formation and rainfall thereby maintaining the water cycle

Though this process leads to loss of water, it helps in cooling the leaves.

This process will continue as long as there is water present on the surface of the earth.

This process is determined by the availability of water in the soil. 

Does not involve any uptake and circulation of minerals and nutrients.

Transpiration helps in circulation of minerals and nutrients in plants.


Evapotranspiration 

The total loss of water from the soil via evaporation and transpiration by plants is referred to as evapotranspiration. The concept of evapotranspiration is vital in relation to agriculture. It is because if evapotranspiration rates can be predicted in ahead, one can ascertain how much irrigation is required for crops.

In addition to irrigation, evapotranspiration also affects soil moisture or the level of water that is in soil. The factors that determine evapotranspiration rate are – the crop type, soil type, temperature, soil moisture level, humidity and wind.

To learn more about transpiration and evaporation, or about any other topic of biology, go through our study materials today. You can also join our live online classes via Vedantu’s app.

FAQ (Frequently Asked Questions)

1. Which Part of the Plant Evaporates Water?

Ans. Leaves have tiny pores called stomata through which plants evaporate water.

2. Name the External Factors that Affect the Transpiration Process?

Ans. External factors that affect the transpiration process are humidity, sunlight, amount of light available, temperature and wind.

3. What is the Difference Between Transpiration and Respiration?

Ans. The process through which water is circulated to different parts of a plant is known as transpiration. Whereas, respiration is the process where plants convert carbon dioxide to oxygen.