WATER AND CARBON - The Hydrosphere And Water Cycle 2 Flashcards
The amount of water present in each store…
Varies over a range of scales from local (e.g. an individual hill slope) to global.
What does the magnitude of each store depend upon?
The amount of water flowing between them.
When does evaporation occur?
When liquid water changes state into a gas, becoming water vapour - it gains energy, normally from solar radiation.
What does evaporation increase?
The amount of water stored in the atmosphere.
What does the magnitude of the evaporation flow vary by?
Location and season.
When will the amount of evaporation be high?
If there is lots of solar radiation, a large supply of water and warm, dry air.
When will evaporation be low?
If there is not much solar radiation, little available liquid water and cool air that is already nearly saturated (unable to absorb any more water vapour).
What can long-term changes in the climate affect? Example?
The magnitude of evaporation. E.g. During the last glacial period, temperatures were lower, so evaporation was lower.
When does condensation occur? Example?
When water vapour changes state to become a liquid - it loses energy to its surroundings. It happens when air containing water vapour cools to its dew point (the temperature at which it will change from a gas to a liquid), e.g. when temperatures fall at night due to heat being lost to space).
What happens to water droplets in the atmosphere after condensation?
They can stay in the atmosphere or flow to other subsystems, e.g. when water vapour condenses, it can form dew on leaves and other surfaces - this decreases amount of water stored in atmosphere.
What does the magnitude of the condensation flow depend on? Example?
The amount of water vapour in the atmosphere and the temperature? If there is lots of water vapour in the air and there’s a large or rapid drop in temperature, condensation will be high.
What is the main flow of water from the atmosphere to the ground?
Precipitation
What are clouds?
A visible mass of water droplets or ice crystals suspended in the atmosphere.
What is cloud formation the result of?
Air in the lower layer of the Earth’s atmosphere becoming saturated due to epithet or both of two processes: cooling of the air and an increase in water vapour.
When cloud droplets from they…
…eventually fall as rain.
What is the first process that leads to formation of clouds?
Evaporation.
Once condensation has occurred, what process happens next for cloud formation?
Condensation
What are the three factors that can cause warm air to cool, leading to precipitation?
Other air masses, topography and convection.
How do other air masses cause warm air to cool, leading to precipitation?
Warm air is less dense than cool air. So when warm air meets cool air, the warm air forced up above the cool air. Cools down as it rises. Results in frontal precipitation.
How does topography cause warm air to cool, leading to precipitation?
When warm air meets mountains, its forced to rise, causing it to cool. Results in orographic precipitation.
How does convection cause warm air to cool leading to precipitation?
When the sun heats up the ground, moisture on the ground evaporates and rises up in a column of warm air. A it gets higher, it cools. This results on convection precipitation.
Three types of precipitation
Frontal precipitation, orographic precipitation and convective precipitation.
Water droplets caused by condensation are too…
Small to form clouds on their own.
For clouds to form what has to be present? And what do they do?
Tiny particles of other substances (e.g. dust or soot) to act as cloud condensation nuclei. They give water a surface to condense on. This encourages clouds to form, rather than allowing the moist air to disperse.
What is the driving force behind cloud formation and precipitation?
The global atmospheric circulation model.
