Lecture panel 1 Flashcards
Used by Egyptians 5000 years ago
Stream gauges
Who used rainfall gauges 3200 BP?
India and China
Why first correctly described the hydrologic cycle and when?
Greek philosophers 2200 BP
How did da Vinci measure streamflow?
put inflated bladder in stream and followed it, walking while measuring distance and time
Angle between H on water molecule
105 (or 104.5)
What properties of water does its shape create?
- large latent and specific heat capacity
- cohesive nature
- large surface tension
- “universal solvent”
specific weight - where is it max for water?
weight per unit volume - max at ~4C
What is dynamic viscosity?
tangential force per unit area required to move one horizontal plane wrt another plane at unit velocity
What temp does water have max density at?
4C
What causes freeze-thaw processes?
expansion of water in solid state
What is the difference between freezing fresh water vs salt water?
salt water freezes at its maximum density, which allows sea ice to occur without overturning
What would the freezing and melting points of water be without H-bonding?
freeze -100C
melt -91C
What is unique about Earth in the solar system (regarding water)
- Large reservoirs of liquid water
- situated where water can exist in all three phases (conditions close to triple point of water)
How does pressure affect ice melting point?
pressure reduces ice melting point
What is specific heat?
amount of energy required to raise the temperature of a substance by a single degree
What is water’s specific heat, and why is it high?
What affects does this have?
- 2 KJ/kg/K
- it is high because if H bonding
- makes water a good habitat for aquatic species, allows warm blooded species to regulate their temperature
- moderates climate
What does water’s high heat capacity mean for heat transportation by oceans?
- oceans responsible for 1/4 to 1/3 of all heat transported to the poles
- greatly moderate climate
What is the heat capacity of oceans compared to the atmosphere?
120x
latent heat of vapourization
quantity of heat absorbed (released) when unit mass of a substance vapourizes (condenses)
latent heat of fusion
quantity of heat absorbed (released) when a unit mass of substance melts (freezes)
What is a consequence of water’s latent heat as it cools in soil?
Soil temperature around water will increase, as calories are released by the phase transition from liquid to solid.
What does surface tension allow?
- allows water to adhere to a wet surface
- allows for capillarity (important for soil water movement)
what do water’s solvent properties mean for earth and life processes?
- -important for biogeochemical cycling, chemical erosion, and life processes
- in rivers, dissolved load is a significant portion of all material transported by rivers to oceans (could exceed suspended load)
What percent of sediment load in Lake Ontario is dissolved?
92%
What is the most important greenhouse gas? What would surface temp be without it?
Water vapour - surface temp would be -18
What property must a water column have for freezing?
isothermal
What shape are water droplets?
Small are spheres, large are donuts due to surface tension
Water helps Earth absorb a lot of energy from the sun in the range
infrared - emission spectra from earth significantly altered from that of black body
