ATOC 181 Lecture Notes - Lecture 4: Intertropical Convergence Zone, Wind Profiler, Hurricane Hunters
7 Jun 2018
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LESSON 5- Water Cycle
Main Components of Water Cycle
• Evaporation: Change of liquid water from oceans, lakes, rivers evaporated into the
atmosphere. Can also leave land. From plants, it is called transpiration (10% of
evaporation)
• Transpiration: liquid water from plants evaporates into the atmosphere
• Evapotranspiration: combination of both evaporation and transpiration from land only
(water vapor which leaves from land surfaces, lakes, rivers, plants, disregard oceans)
• Condensation: water vapour in the atmosphere condense into clouds (liquid). Water
vapour climbs into atmosphere and condense, which will form liquid clouds
• Precipitation in the form of rain, snow and ice
Hydrological Cycle
• Water is transported from the surface to the atmosphere (liquid to gas)
• Water vapour condenses to form clouds
• In atmosphere, water vapour also transported vertically to form clouds, but
transportation towards land is favored
• Water falls back to the Earth as rain, hail or snow (precipitation)
o is ground water storage
o Fresh water storage
o Water storage in the form of ice, snow in the form of glaciers which will eventually
come back to the oceans later.
• Precipitation (rain, snow, hail) is the primary mechanism for transporting water from the
atmosphere to the surface (lands or oceans)
• Different form of transport: flux (from ocean to air, from air to land/oceans)
• Sublimation happens in very cold air, snow/ice will immediately become water vapour.
Condense and then precipitate
• Rain when fall in Earth can fall as ice, snow, and will stay there. In spring, snow will melt
and will increase the amount of water in lakes and rivers
• This precipitation from lands will come back to oceans
• Infiltration in ground can happen, can stay here or get into underground storage and then
can go to oceans, lakes or form springs
• Is the amount of rain falling on the Earth surface or smaller than the amount of water
evaporating from the surface?
Yearly Water Fluxes
• Show transport of water in different forms
• Can derive some laws of nature
• Complicated to find the nbs: observation values in this case
• Observation (transport in 1000km3 per year): amount of transport during one year
o Need to multiply nb on chart by 1000km3
o Vapour transport: 38 000
find more resources at oneclass.com
find more resources at oneclass.com
o Runoff return (to lakes and oceans) = 3000 + 35 000= 38 000
• Precipitation over land and over oceans are separated
• Total evaporation-transpiration over land per year: 71 000 km3
• More precipitation or more evaporation on Earth each year?
o Evaporation transpiration: 71+430 = 501 000 km3 per year
â–Ş Amount of water evaporated each year from both ocean and lands
o Precipitation: oceans and lands: 501 000 km3 per year
• As much water falling on Earth as water evaporating.
• If more precipitation, after a certain time, our surface will be totally covered, will be living
in water
• If more evaporation, water on lands and oceans will disappear, happen in 100 of 1000 of
millions of years, not 10 years
• If assume that no precipitation, take the water storage over land and in oceans and look
at the amount that evaporates each year, how long will it take to evaporate all water on
land and in oceans? CALCULATE THIS
Yearly Precipitation & Evaporation
• The total yearly amount of precipitation (onto oceans an land) is equal to the amount of
evaporation and transpiration from oceans and lands
• Precipitation over the oceans is ~3.5 times more than over lands
• Total yearly amount of precipitation is more than 35x the atmospheric water storage
• About 85% of total evaporation is from the oceans
• About 1300 km3/day evaporate from the earth surface (oceans, lakes, rivers, the soil and
leaves of plants)
• Precipitation per year: 501 000 km3/year
• Precipitation per day: 501 000/365 days = 1372 km3/day
• Annual precipitation is more 30x the atmospheric storage (total capacity to hold water)
o Atosphere’s capacity to hold water: 13 000 km3
o Total precipitation: (392+ 109) = 501 000 km3
o Ratio: 38.5
• Evaporation from the oceans represent 85% of the earth total evaporation, while
evaporation (and transpiration) over land represents 15%
o Total evaporation: 501 000
o Evaporation over oceans: 430 000
o Over land: 71 000
o Oceans: 85.8%
o Land: 14.2%
• More precipitation over oceans than over land (~3x), oceans cover much larger part, not
seen much while can see precipitation over land.
Precipitation (Monthly Average)
• The desert in Australia and Sahara Desert = not have much precipitation. Same for coast
of Chile
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Main components of water cycle: evaporation: change of liquid water from oceans, lakes, rivers evaporated into the atmosphere. Water vapour climbs into atmosphere and condense, which will form liquid clouds: precipitation in the form of rain, snow and ice. Hydrological cycle: water is transported from the surface to the atmosphere (liquid to gas, water vapour condenses to form clouds. Condense and then precipitate: rain when fall in earth can fall as ice, snow, and will stay there. In spring, snow will melt and will increase the amount of water in lakes and rivers: this precipitation from lands will come back to oceans. Infiltration in ground can happen, can stay here or get into underground storage and then can go to oceans, lakes or form springs. If more precipitation, after a certain time, our surface will be totally covered, will be living in water.
