The work discusses the principles of evaporation as one of the processes in the hydrologic cycle and the different methods to estimate the evaporation rate. Four different methods namely the energy balance, aerodynamics, combination method and Priestley-Taylor method are included in the discussion. In the end there are some examples with solutions.
Evaporation is the process that liquid water enters the atmosphere as water vapour and replenishes the humidity of the air. It is also considered as the pathway in which the water travels from its liquid state back into the hydrologic cycle as an atmospheric water vapor. Water bodies such as oceans, seas, lakes and rivers provide nearly 90 % of the moisture in the atmosphere through evaporation, as some study reveals.
Table of Contents
- 1.0 Introduction
- 2.0 Evaporation
- 3.0 Principles of Evapotranspiration
- 4.0 Estimation Methods of Evaporation
- 4.1 Energy Balance Method
- 4.2 Aerodynamic Method
- 4.3 Combination Method
- 4.4 Priestley-Taylor Method
- 5.0 Sample Problems
- References
Objectives and Key Themes
This ebook aims to explain the principles of evaporation within the hydrological cycle and present various methods for estimating evaporation rates. It focuses on providing a clear understanding of the process and practical tools for calculation.
- The process of evaporation and its role in the water cycle.
- Factors influencing evaporation, including energy supply and atmospheric conditions.
- Different methods for estimating evaporation rates (energy balance, aerodynamic, combination, and Priestley-Taylor methods).
- Application of these methods in practical scenarios.
- The concept of potential evapotranspiration (PET).
Chapter Summaries
1.0 Introduction: This introductory chapter sets the stage by defining evaporation as the process where liquid water transforms into atmospheric water vapor, replenishing air humidity. It highlights the significant contribution of water bodies to atmospheric moisture and briefly outlines the ebook's focus on exploring different evaporation rate estimation methods, specifically the energy balance, aerodynamic, combination, and Priestley-Taylor methods.
2.0 Evaporation: This chapter delves into the fundamental process of evaporation, emphasizing the crucial role of solar heating. It explains how evaporation contributes to cloud formation and precipitation, completing the water cycle. The chapter also details two primary influencing factors: the energy supply for vaporization (solar radiation) and the combined effect of wind velocity and specific humidity. Further, it lists meteorological factors impacting evaporation, including solar radiation, wind, relative humidity, and temperature.
3.0 Principles of Evapotranspiration: This chapter explores evapotranspiration, the combined process of evaporation from the land surface and transpiration from vegetation. It builds upon the previous chapter by adding the supply of moisture at the evaporative surface as a key influencing factor. The concept of Potential Evapotranspiration (PET), representing evaporation from a well-vegetated surface with ample water supply, is introduced and defined. The chapter clarifies that PET is a measure of the atmosphere's ability to remove water through evaporation and transpiration, irrespective of water limitations.
4.0 Estimation Methods of Evaporation: This chapter presents various methods used to estimate evaporation rates. It details the Energy Balance Method, which calculates latent heat flux as a residual term in the energy balance equation, offering simplified calculations when sensible and ground heat fluxes are negligible. The Aerodynamic Method is discussed, focusing on vapor transport governed by humidity gradients and wind speed. Finally, the Combination Method is introduced, combining aspects of both the Energy Balance and Aerodynamic methods for a more comprehensive estimation.
Keywords
Evaporation, Evapotranspiration, Potential Evapotranspiration (PET), Energy Balance Method, Aerodynamic Method, Combination Method, Hydrological Cycle, Water Vapor, Solar Radiation, Wind, Humidity, Temperature.
Evaporation: A Comprehensive Guide - Frequently Asked Questions
What topics are covered in this ebook?
This ebook provides a comprehensive overview of evaporation and evapotranspiration. It covers the fundamental principles of evaporation, its role in the hydrological cycle, and various methods for estimating evaporation rates. Specific topics include the energy balance method, aerodynamic method, combination method, and the Priestley-Taylor method. The ebook also explains the concept of potential evapotranspiration (PET).
What are the main objectives of this ebook?
The ebook aims to explain the principles of evaporation within the hydrological cycle and to present various methods for estimating evaporation rates. It focuses on providing a clear understanding of the evaporation process and practical tools for calculation.
What are the key themes explored in the ebook?
Key themes include the process of evaporation and its role in the water cycle; factors influencing evaporation (energy supply, atmospheric conditions); different methods for estimating evaporation rates; application of these methods in practical scenarios; and the concept of potential evapotranspiration (PET).
What methods for estimating evaporation rates are discussed?
The ebook details four primary methods: the Energy Balance Method, the Aerodynamic Method, the Combination Method, and the Priestley-Taylor Method. Each method is explained in detail, outlining its principles and application.
What is the Energy Balance Method?
The Energy Balance Method calculates latent heat flux as a residual term in the energy balance equation. Simplified calculations are possible when sensible and ground heat fluxes are negligible.
What is the Aerodynamic Method?
The Aerodynamic Method focuses on vapor transport governed by humidity gradients and wind speed.
What is the Combination Method?
The Combination Method combines aspects of both the Energy Balance and Aerodynamic methods for a more comprehensive estimation of evaporation rates.
What is Potential Evapotranspiration (PET)?
Potential Evapotranspiration (PET) represents the evaporation from a well-vegetated surface with ample water supply. It is a measure of the atmosphere's ability to remove water through evaporation and transpiration, irrespective of water limitations.
What factors influence evaporation?
Several factors influence evaporation, including solar radiation, wind speed, relative humidity, temperature, and the availability of moisture at the evaporative surface.
What is the role of evaporation in the hydrological cycle?
Evaporation plays a crucial role in the hydrological cycle by replenishing atmospheric water vapor, which eventually contributes to cloud formation and precipitation.
Where can I find sample problems?
The ebook includes a dedicated chapter with sample problems to illustrate the application of the discussed evaporation estimation methods.
- Quote paper
- Florante Jr Poso (Author), 2019, Estimation Methods of Evaporation. Examples for Revision, Munich, GRIN Verlag, https://www.grin.com/document/464154
