chapter 7 Flashcards
what pourcentage of earths water is in the atmosphere
0.03%
Hydrologic cycle, or water cycle
the movement of water throughout the atmosphere, hydrosphere, lithosphere, and biosphere
Hydrogen bonding
the positive (hydrogen) side of a water molecule attracts the negative (oxygen) side of another, polarity
Surface tension
allows a steel needle to float lengthwise on the surface of the water, even though steel is much denser than water, this surface tension allows you to slightly overfill a glass with water
Capillarity
caused by hydrogen bonding; when a towel draws water through its fibres because hydrogen bonds make each molecule pull on its neighbour
what happens after 4°C with water
water behaves differently from other compounds, it expands as more hydrogen bonds form among the slowing molecules, creating the hexagonal crystalline structure characteristic of ice
Phase change
the change in phase, or state, among ice, water, and water vapour; involves the absorption or release of latent heat
Melting and Freezing
phase changes between solide and liquid
Condensation
water vapour in the air becomes liquid water
Evaporation
liquid water becomes water vapour
Vaporization
when water is at boiling temperature and become water vapour
Deposition
water vapour attaches directly to an ice crystal, landing to the formation of frost
Sublimation
ice changes directly to water vapour
ice phase
It contracts in volume but increases in density, (as the same number of molecules now occupy a smaller space), 80 calories is needed to change phases
why does ice floats
Pure ice has 0.91 times the density of water, so its floats, without that, much of earth’s freshwater would be bound in masses of ice on the ocean floor, it contains air bubbles
Latent heat
heat energy is stored in one of three states - ice, water, or water vapour. The energy is absorbed or released in each phase change from one state to another. Heat energy is absorbed as the latent heat of melting, vaporization, or evaporation. Heat energy is released as the latent heat of condensation and freezing (or fusion)
liquid phase
100 calories is needed for a change of phase
Latent heat of vaporization
the heat energy absorbed from the environment in a phase change from liquid to water vapour at the boiling point
Latent heat of condensation
the heat energy released to the environment in a phase change from water vapour to liquid
Latent heat of sublimation
the heat energy absorbed or released in the phase change from ice to water vapour and vise versa, absorbe 680 cal for a change of phase
gas phase
540 calories is needed to change the gas phase into liquid phase, under normal sea level pressure
what happens when global temperature rise
evaporation increases from lakes, oceans, soils, and plants, amplifying the concentration of water vapour in the atmosphere and strengthening the greenhouse effect over Earth
Effect of climate change on water
as water vapour increases, precipitation patterns will change and the amount of rainfall will likely increase during the heaviest precipitation events, A 7% vapour will increase for every 1°C of warming
Humidity
the amount of water vapour in the air, it is primarily a function of the air temperature
Relative Humidity
the ratio of water actually in the air (content) to the maximum water vapour possible in air (capacity) at that temperature; expressed as a percentage
Saturation equilibrium
equilibrium in the maximum amount of water vapour that can exist in a volume of air at a given temperature, and the rates of evaporation and condensation are the same
Saturation
state of air that is holding all the water vapour that it can hold at a given temperature, known as the dew-point temperature
Dew-point temperature
the temperature at which a given mass of air becomes sautéed, holding all the water it can hold. Any further cooling or addition of water vapour results in active condensation
Frost point
the temperature at which the air becomes saturated, leading to the formation of ice on surfaces
why does the rate of evaporation varies from morning to afternoon
because relative humidity changes with temperature