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Flashcards in Precipitation and evaporation Deck (21):

Short term precipitation

- moniitoring sever stroms
- weather forecasting
- flood monitoring and control


Medium term precipitation

water resource management
- nature conservation
- domestic use
- hydroelectric power generation
- irrigation management


Long term precipitation

- climate prediction
- hydrological planning


Atmospheric rivers

are relatively narrow regions in the atmosphere that are responsible for most of the horizontal transport of water vapour outside the tropics


Precipitation water

the depth of water in a column of the atmosphere, if all the water in that column were precipitated as rain


Latitudinal distribution of energy

- geometrical relations of the earths orbit cause seasonal and latitudinal variation in the receipt of solar energy
- given energy is spread out over larger areas at high latitudes
- latitudinal effect is modified seasonally because the earths axis of rotation is tilted at 23.5 degrees


Net radiation

- positive for latitudes below 35 degrees
- total energy input and output must be in balance at all latitudes
- net poleward transfer of energy fluxes, accomplished by air and ocean currents


General circulation

- unequal latitudinal distribution of radiation plus need for conservation of angular momentum of the rotating earth l
- 3 cells (0-30, 30-60, 60-90) plus jet streams and typical surface wind directions
- less dominate in high latitudes where wind circulates in large scale horizontal eddies


General circulation result in (high and low pressure)

- low pressure: regions of rising are near equator and at latitudes of 60 degrees
- Higher pressure: region of descending air near 30 degrees latitude and the poles
- quasi stationary zones of H & L pressure cause moving cyclonic storms
- both dominate weather systems in latitudes


Distribution of precipitation

- equatorial belt is particularly pronounces because of warm easterly winds from both hemisphere
- these carry large amounts of moisture evaporated from tropical oceans that converge in this zone (ITCZ)
- peaks in mid-latitudinal zones, mainly linked to extra-tropical cyclonic storms, developing along polar fronts


high precipitation

- regions with rising air
- near the equator and 60 degrees


low precipitation

- regions with descending air
- near the equator and 30 degrees (Deserts)


Global precipitation patterns

- significant deviations from latitudinal distribution
- precipitation rates are influenced by topography, air temp, frontal activity and wind direction in relation to moisture sources
- mountain ranges cause high P, rain shadow leeward of prevailing winds
- interaction of circulation & topography causes monsoon in Asia
- teleconnections, ENSO


Precipitation formation

- moisture (Water vapour)
- condensation nuclei
- atmospheric cooling
- importation of water vapour


Aondensation nuclei

Provide a surface fro the eater vapour to condense into liquid water upon
- particles floating in the atmosphere
- < 1 micron


Atmospheric cooling

Through the uplift of warm air
- convectional rainfall
- relief rainfall
- cyclonic rainfall


Relief (Orographic) precipitation

- warm, moist air is forced to rise over high areas
- air cools, forming clouds
- air descends, warms and becomes drier
- note rain shadow region at leeward side


Storage gauge measurement

- measures total depth of rain
- manually read, often daily
- maintained as check gauge


Tipping bucket measurement

- measures rain intensity over time
- records time of bucket tip
- electronically logged or telemetered


Measurement accuracy

- spatial variability
- evaporation (loss)
- splash from surroundings (gain)
- wind turbulence (loss


Pathways through vegetation

- interception
- stemflow
- through-flow and canopy drip
- infiltration