GEOG220 Hydrology Flashcards
What happens when temperature increases (water, latent heat)?
Increased temp = more latent heat consumed, breaking down hydrogen bonds = availability for evapouration
How much radiation is re-emitted as longwave radiation?
15%
How much longwave radiation is converted into latent heat and sensible heat?
Latent Heat: 24%
Sensible Heat: 7%
Energy Balance Equation
Rn = LE + H + S
Rn (net radiation)
H (sensible heat)
LE (latent heat)
S (energy store/flux)
Sensible Heat vs Latent Heat
Sensible heat is the heat we can feel, latent heat is the energy used to break bonds between water molecules.
Arid Climate: Sensible v Latent Heat
Net radiation is converted into sensible heat, because water not available.
Humid Climate: Sensible v Latent Heat
Net radiation converted to latent heat for evap, because water is available.
Watershed
Area upstream of a point, known as catchment/basin/contributing area.
Pool
store of water (ocean, lake, ice, atmosphere, gw)
Flux
Way water moves between pools, like evaporation, precip, discharge, etc.
What is the main cooling mechanism?
Uplift!!!
Precipitation and Evaporation
Air temp controls the max amount of water vapor it can hold. Air cools (uplift) below dew point temperature = saturated = condensation = precip.
Water Balance Equation
P = Q + E + DeltaS
P = precip
Q = runoff
E = evap
DeltaS = chnage in storage
Precipitation
Flux of water from the atmosphere to the surface, in different forms (dew, mist, fog, rain).
Global Average Annual Precip
High over equator (where warm air holds more moisture) and low over poles/mid lat (cold air holds little moisture).
There are temporal variations (NZ has low variation, high supply).
Climate Controls on Aridity
Water vapour transports energy. Global circulation controls water availability.
Energy + water control aridity.
Energy + water high at equator, energy + water low near subtropical highs.
Saturated v Unsaturated Air
When air cools below its dew point = condensation.
If air unsaturated = evap (so long as there is energy to break bonds).
Effect is NON-LINEAR, getting stronger with warming air.
True of False, an air parcel can reach dew point temperature through warming and cooling
True, increase in temp = will reach dew point through warms. Decrease in temp = will reach dew point through cooling (like breathing out)
Convective Rainfall
Strong heating of land = air rise. Rising = gradual cooling = water vapour condenses. Produces heavy rain from quick rising.
short duration, intense. 30% of NZ rainfall.
Orographic Rainfall
Prevailing wind uplifted by topography. Rises, cools, dondenses, heavy precip on windward side.
Frontal/Cyclonic Rainfall
Precip caused by aur mass moving in.
Long duration. If cold front = more intense (displaces warm air and rapidly pushes it up to create intense precip).
What are the 3 types of rainfall?
Convective, Orographic, Frontal/Cyclonic.
Types of Precip Measurements
Direct, aerial, indirect.
Direct Rainfall Measurement (at a point)
Rain gauges
Little bucket, rain drops in, sensor tips, flicks switch. Flick switch frequency = amount of rainfall.