Phsyical Geography Flashcards
(13 cards)
Describe how throughflow occurs on slopes.
Once water from the surface has been infiltrated there is then percolation through the soil which flows laterally. Steep slopes tend to reduce the amount of infiltration of water into the ground which this water can flow quickly down to rivers through overland flow.
Describe and explain the formation of gorges.
A gorge is a steep sided, narrow valley with a river flowing through it. At the base of a waterfall the pressure and hydraulic action of the falling water causes the softer rock which is underneath to erode forming a plunge pool. Over time, this continues to erode backwards, undercutting the harder rock on the surface. Eventually the over hang is so great that the hard rock can’t support its own weight and therefore collapses - rockfall. Sediment from the warn away rock is carried downstream further adding to the erosion of the steep walls.
Causes of a flood (physical).
- Intense/prolonged rainfall
- Snow melt
- Saturated ground
- Impermeable rock
Causes of flooding (human)
-Population growth
-Urban growth - building on floodplains creates impermeable surfaces; increases surface runoff.
-Deforestation
How does the natural landscape impact storm hydrographs.
-Steeper slopes allow more overland flow compared to infiltration so this increases the runoff speed and therefore makes the lag time shorter as well as there being a higher peak discharge on the hydrograph.
- Where as more gentle slopes encourage infiltration which would result in the hydrograph being flatter with a longer lag time as well as a lower peak discharge as a result.
Explain the enhanced green house effect.
Earths greenhouse gases such as carbon dixiode and methane trap heat in the atmosphere therefore absorbing outgoing longwave radiation. This as a result increases the atmospheres temperature. The enhanced greenhouse effect is an increase is these gases (co2). This can be caused due to human activities such as in vehicles the exhaust pipe releases chemicals into the atmosphere as well as industrial processes.
Define sensible heat transfer
The movement of heat energy from warmer surfaces to colder surfaces through conduction.
Define evaporation
The process where water is transformed into a gas - water vapour, when heat is applied
Explain how frontal uplift of air may result in precipitation
At cold fronts warm air overrides the cold air so it is the warm air is forced upwards over the cold air. As a result the temperature drops which leads to condensation and therefore precipitation occurs.
Describe and explain the latitudinal pattern of radiation in the global energy budget.
The atmosphere is an open system which is a system where energy can cross its boundary to the surrounding environment and vise versa. The general pattern is that there is a deficit at the poles as the incoming solar radiation exceeds outgoing long wave radiation and an excess at the equator as outgoing radiation now exceeds the incoming solar radiation. The angle of the sun is more overhead at the equator so incoming solar radiation is greater compared to at the poles but outgoing long wave radiation is greatest at around 45C both north and south and the sun rays are spread over a larger area at the poles. As the earth is naturally curved, the incoming shortwave radiation arrives at more of a steeper angles at low latitudes compared to shallower angles and high latitudes hence why it is more spread out as it has to travel through more areas within the atmosphere. As snow and ice have have high albedos, at higher altitudes they reflect more of the incoming shortwave radiation instead of absorbing it.
