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Water Cycle - Coggle Diagram
Water Cycle
Transfers
Groundwater flow - Occurs when soil is underlain by permeable rocks. Water percolates deeper underground, and migrates trhough rock pores and joints deep underground, before re-emerging through springs and seepages
Evapotranspiration - Evaporation from the leaves of plants, plus transpiration from the stomata of plants releases water vapour that rises into the atmosphere
Condensation - Water changing state from a gas to a liquid, occuring when water is cooled to its dew point. Clouds form through condensation, and when they do large amounts of latent heat is releases, which can aid the formation of tropical storms
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Run off - Happens when there is impermable ground, or saturated ground
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Overland flow - Flow of water along the ground's surface, in clearly defined channels, can also be caused when saturation causes the water table to rise
Throughflow - Horizontal movement of water sub-surface, in the upper layers of the soil, often when the soil is completely saturated
Stores
Aquifers - Underground layers of rock that are porous and permeable enough to hold significant amounts of groundwater
Glaciers - Water stored in cryosphere, water is frozen into slow moving freshwater glaciers, however with climate change this store is decreasing. Large amount of remaining water, along with groundwater
Oceans - Largest store in the water cycle, holds the massive majority of the earth's water. Contains 97% of water.
Soil moisture - Water can be held in the soil for extended periods of time, particularly when lower rock is impermeable. Can be transferred back to the surface through capillary rise
Surface bodies - Water is also held in rivers, lakes and reservoirs above ground
Atmosphere - Water is held in the atmosphere in the form of water vapour, which contributes to the greenhouse effect. Contains less than 0.01% of water
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Clouds and Rainfall
Types of rainfall
Relief - When there is an orographic barrier, such as mountains, warm air is forced to rise over the obstacle, cool down, reach dew point and rain. This often leads to a 'Rain shadow desert' on the other side, as rainfall fails to pass over the barrier
Convectional - Localised heating leads to warm air rising, which then cools and precipitates higher up
Frontal wedging - Warm air meets cold, and a front forms, and as the warm air is less dense, colls as it rises, reaches dew point and causes precipitation
How rain forms
Collision coalescence model - Small cloud droplets collide, joining into larger droplets, before reaching critical mass and falling as rain
Clouds form during condensation in the atmosphere, when the air reaches its dew point, and becomes saturated with vapour. Convectional heating forms cumuliform clouds, with vertical development. Stratiform clouds occur due to advection as clouds move across cooler surfaces
Bergeron process -
Water is found in all 3 phases in tall CB clouds – temperatures in the towering DB cloud drop well below OC.
Ice crystals are growing faster than water droplets here because saturation vapour pressure for ice is lower than for water so ice forms at the expense of liquid water
Water below OC is called supercooled water – but this freezes on contact with a surface eg aeroplane windows – similar to ice crystals falling through supercooled water in a tall CB cloud > ice crystal grows
Ppt formed as ice but falls often as rain as it warms on descending and melts. You might experience it on the ground as rain but it was ice higher up
Lapse rates
Environmental lapse rate
Vertical temperature profile of the lower atmosphere at any given time. 6.5 degrees per Km. At a certain height, air stops rising and becomes stable as it is heavier than its surroundings.
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Feedback loops
Positive
Higher temperature leads to more evaporation, leading to more water vapour in the atmopshere, which is a greenhouse gas, which warms the atmosphere, which drives more evaporation
If the temp rises, Greenland ice caps will melt, diluting the salinity of the nearby gulf stream chimneys, sinking the gulf stream, plunging Europe into a fresh ice age
Drainage basins exist in dynamic equilibrium, so if there is excessive rainfall, channel flow will increase to remove it from the basin
Negative
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If there is excess rainfall in a drainage basin, river flow and evapotranspiration increase, and aquifers store excess water, which restores the basin to its equilibrium
In drought years, when water lsot through transpiration in plants is not replenished, plants can shed their leaves to reduce transpiration, accounting for the lower root uptake