The Water Cycle

• Flow / Transfer - a form of linkage between one store / component and another that involves the movement of energy or mass
• Input - addition of matter / energy into a system
• Store / Component - part of the system where energy / mass is stored or transferred
• System - a set of interrelated components working towards some kind of process 
• A cascading system - open systems forming part of a chain, e.g the subsystems within Earth
• Interlocking relationships among the atmosphere, lithosphere, hydrosphere and biosphere have a profound effect of Earth's climate and climate change.

Water Stores - 

• Hydrosphere = discontinuous water layer at / near the Earth’s surface, including surface, ground and atmospheric water
• Oceanic water = water in oceans but not within inland seas. Covers approximately 72% of the Earth’s surface. Divided into 7 oceans and smaller seas. The water tastes salty as it contains dissolved salts. These salts allow it to stay as liquid water under 0°. 
• Cryospheric water = water locked up on Earth’s surface as ice e.g. sea ice, ice sheets, ice caps
• Terrestrial water = groundwater, soil moisture, lakes, rivers, wetlands
• Atmospheric water = water found in the atmosphere (mainly water vapour with some liquid water)

Factors Driving the Change in Magnitude of Water Stores - 

Water exists in solid, liquid and gas form. Energy, in the form of latent heat, can be absorbed or released (process dependent).

Latent Heat = heat energy that is taken in or given out by a substance when it changes state

• Evaporation – this occurs when energy from solar radiation hits the surface of water or land and causes liquid water to change from a liquid to a gas. The rate of evaporation depends on –
  • The amount of solar energy
  • The availability of water
  • The humidity of the air (closer to saturation point = slower evap)
  • The temperature of the air (warm air can hold more vapour)
• Transpiration - all terrestrial plants lose water through transpiration (where water is transported from the roots of a plant to leaves and then lost through pores (stomata) on the leaf surface).
  • As water evaporates, it uses latent heat and so cools its surroundings.
• Condensation – as air cools, it is able to hold less water vapour. If cooled sufficiently, it will get to a temperature at which it becomes saturated. This is the dew point temperature. Excess water will then be converted into liquid through condensation. They have to condense on condensation nuclei (something to condense on) or surfaces. It the surface is below freezing point, the vapour changes to a solid (hoar frost). It causes all forms of precipitation.
• Cryospheric Processes - The most recent glacial period started 2.58milion years ago and is still going on. It is called the quaternary glaciation. During this time there were -
  • Glacial periods when, due to the volume of ice on land, sea level was 120m lower than it is now. Continetal glaciers covered Europe and NA. (interruption…