Principles and Processes of Hydrology 1 Flashcards
What is the water balance equation?
(P-E) + Uk + Ui + Q + deltaS = 0
What are the 4 fundamental laws that form the basis of hydrology?
- Conservation of mass
- Newtons law of motion
- laws of thermodynamics
- Fick’s law of diffusion
Dimension
The ratio of the magnitude of the quantity (of water) to the magnitude of a standard unit of measurement.
Dimension of Force
[F] in Newton
Dimension of Mass
[M] in kilograms
Dimension of Length
[L] in meters
Dimension of Time
[T] in seconds
Dimension of Temperature
[Theta] in Kelvin
Integers
[Mâ] where a is the integer
How are units of Mass and units of Force related by Newtons 2nd law?
[F] = [M A] = [M L T^-2]
Dimension of Energy (what it equals)
[E] = [F L]
Dimensionless quantities
Quantities obtained by counting, denoted as [1]
Units
The arbitrary standards in which magnitudes of quantities are expressed.
(Expresses the ratio of the magnitude of a quantity to the magnitude of an arbitrary standard)
Systeme International (SI)
The international standard for science (the metric system)
The density of water
1000 kg/m^3
An equation that is dimensionally homogenous
An equation that is describing a physical relation that has the same dimensions on both sides of the equal sign.
What are the 3 modes of energy exchange?
- Latent heat
- Sensible heat
- Electromagnetic radiation
What is an f(x) of the weight of the overlying atmosphere?
Pressure
Saturation vapor pressure e^*
The maximum vapor pressure, the greatest amount of water that the atmosphere can hold. Can be estimated as an f(x) of temperature.
Equation for e*
611 * exp(17.27*T / T- 273.3) (For a horizontal liquid surface)
Estimate of the atmospheric pressure
1000 mb
Amount of water vapor in percentage of total atmospheric volume
0-4%
Range of vapor pressure in mb
0-40mb
Saturation
Condition where air is holding as much water as possible. At maximum capacity, it precipitates. Changes with temperature and pressure.
Absolute humidity
Ratio of mass H20/volume of air (in g/m^3).
Specific humidity
Ratio of mass H20/mass of total air (in g/kg)
Specific humidity mixing ratio
Ratio of mass H20/mass of DRY air (in g/kg)
Relative humidity
A ratio measuring the percentage of saturation of actual H20 vapor/maximum H20 vapor. Changes with temperature and pressure.
What change in temperature leads to a lower relative humidity if all else remains constant?
An increase in temperature
Dew point
The temperature to which air must cool for condensation to occur (saturation).
Precipitable water
The amount of water vapor in a column of the atmosphere extending from surface to top of atmosphere. Dimensions are [L] and it represents the depth of water that would result from the complete condensation and precipitation of all water vapor above a particular location.
Evaporation
The change of state from liquid to gas
Transpiration
Vapor loss form stomata in plant leaves
Evapotranspiration
Net transfer (loss) of water vapor from wet surfaces and vegetation into the atmosphere.
Vapor exchange
Dry air of temperature Ta lies above a horizontal water surface with the temperature Ts. Some water molecules have sufficient energy to enter the air above. The number of those molecules increases as Ts increases.
e(a)
A steady state vapor pressure at specific given wind and temperature conditions. And f(x) of Ta and wind speed.
Evaporation rate is proportional to ______
e*s - ea
Controlling factors for evapotranspiration
- water
- energy
- vapor pressure
- wind
- vegetation
If e*s > ea
Evaporation is occurring
If e*s < ea
Water is condensing on the surface
If e*s = ea
Neither condensation nor evaporation is occurring
Latent Heat of vaporization
The quantity of heat energy that must be absorbed to break the hydrogen bonds when evaporation takes place. The same quantity is released when when bonds are reformed and condensation occurs.
