(LECTURE 5) EVAPORATION AND EVAPOTRANSPIRATION Flashcards
is the conversion of liquid water from lakes, streams, and other bodies of water to water vapor.
Evaporation
Examples of Evaporation
-Drying clothes
-Sweating
-Drying wet floors
-Ironing clothes
-Cooling hot drinks
-Salt production
-Hair drying
-Nail polishing remover
is the process by which water is emitted from plants through the stomata, small openings on the underside of leaves that are connected to the vascular tissue.
Transpiration
describe the combined losses of water due to transpiration and evaporation.
Evapotranspiration
used interchangeably with evapotranspiration but technically, it refers to the sum of ET and water used by the plants for tissue building processes.
Consumptive Use
FACTORS AFFECTING EVAPORATION
-Temperature
-Wind speed
-Surface area
-Humidity
-Effects of water quality
-Atmospheric pressure
On increasing the temperature, the rate of evaporation also increases.
Temperature
At higher temperature, the 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.
Temperature
When the clothes are spread out on a clothesline on a windy day, they will dry up quicker than on a still day.
Wind speed
Wind speed and rate of evaporation are directly proportional to each other.
Wind speed
As the surface area increases, the rate of evaporation also increases.
Surface area
The more area is exposed to air, allowing water molecules to acquire more heat energy from the surroundings
Surface area
The larger the surface area, the larger the opportunity for the water to escape or evaporate.
Surface area
a measure of the amount of water vapor in the air.
Humidity
The more saturated the air, the slower the evaporation process.
Humidity
Impurities and dissolved substances can alter the evaporation rate.
Effects of water quality
Lower air pressure makes it easier for water to evaporate.
Atmospheric pressure
Evaporation rate is faster in fresh water due to high vapor pressure.
Effects of water quality
At high altitudes where the air pressure is lower, water boils at a lower temperature. Cooking times vary on different altitude.
Atmospheric pressure
describes the total water removed from an area by transpiration (release of water vapor from plants) and by evaporation of water from soils, snow, and water surfaces.
EVAPOTRANSPIRATION
help in moisture conservation because they decrease the rate of evaporation.
Mulches
METHODS OF MEASUREMENT OF EVAPORATION
DIRECT METHOD
- water budget method
- lysimeter
- class A evaporation pan
INDIRECT METHOD
- mass transfer
- energy balance
- empirical methods
•penman equation
•meyer’s formula
device used to measure the amount of water that moves through soil, helping researchers understand water balance, evapotranspiration, and soil-plant interactions.
lysimeter
METHODS OF DETERMINING ET
-field experimental plots
-Soil water studies
-Integration methods
-Inflow-outflow method
-Remote sensing techniques
the quantity of water applied in these plots is kept small to avoid deep percolation losses and surface runoff is measured.
Field experimental plots
samples are taken at various depths in the root zone
Soil water studies
the water used by plants and evaporation from the water and soil surfaces are combined for the entire area involved
Integration methods
inflow into the area (precipitation), outflow from the area and change in groundwater level are evaluated.
Inflow-outflow method
Advanced methods that can estimate evaporation by analyzing satellite data to understand the energy and water fluxes on the Earth’s surface
Remote sensing techniques
Methods of Measurement of Evaporation
-Direct method
-Indirect method
the amount of water evaporated from a unit surface area per unit of time.
Rate of Evaporation
Direct Method
-Water Budget Method (simplest method)
-Lysimeter
-Class ‘A’ Evaporation pan
-
Indirect Method
-Mass-Transfer Method
-Energy Balance
-Empirical Methods
•Penman Equation
•meyer’s formula
