GEG 3102 Lecture Notes - Lecture 2: Lapse Rate, Ecosystem Services, Evapotranspiration
17 Oct 2016
School
Department
Course
Professor
Lecture 2 – Atmospheric Water
14/09/2016
Lab due next Tuesday by 11:59 pm
Ecosystem services (Provides water & leisure)
Atmospheric Water
- All the water in the atmosphere
• Mostly vapour, but liquid & solid are also present
• Plays a very important role in the redistribution of energy and substances
• Less than 0.001% of the total water
• Estimated to be a layer of 25 mm (1 inch) (S)
• Average global precipitation is ~ 1m/year (Q)
• Residance time = 9.125 days
- TR = S (storage) / Q (flow rate)
• Significant part of the atmosphere & a major greenhouse gas (36-72%)
- Humid air is lighter than dry air
• H2O is lighter than N2
• Water vapour = 0.804 g/L; Dry air = 1.27 g/L (@ STP)
- Dry adiabatic lapse rate:
• Adiabatic (def.) No transfer of heat or matter (closed system)
• When air warms it become lighter, so it rises
- As it rises the air mass will expand and cool
- Will continue rising until the surrounding air is at the same temperature as
the air mass
• Dry lapse rate: 1°C/100m
• As the air cools the relative amount of water increase, which can lead to saturation
- Saturated adiabatic lapse rate:
• When an air mass becomes saturated the moisture will condence and release latenet
heat
• ….
• Saturated adiabatic lapse rate: 0.6°C/100m
- Beacause latent heat is also being released
- Saturation pressure is the pressure exerted by water vapur molecures when the air is
saturated
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Tr = s (storage) / q (flow rate: significant part of the atmosphere & a major greenhouse gas (36-72%) Humid air is lighter than dry air: h2o is lighter than n2, water vapour = 0. 804 g/l; dry air = 1. 27 g/l (@ stp) Dry adiabatic lapse rate: adiabatic (def. ) No transfer of heat or matter (closed system: when air warms it become lighter, so it rises. As it rises the air mass will expand and cool. Will continue rising until the surrounding air is at the same temperature as the air mass: dry lapse rate: 1 c/100m, as the air cools the relative amount of water increase, which can lead to saturation. Saturated adiabatic lapse rate: when an air mass becomes saturated the moisture will condence and release latenet heat, saturated adiabatic lapse rate: 0. 6 c/100m. Beacause latent heat is also being released. Saturation pressure is the pressure exerted by water vapur molecures when the air is saturated.
