global hazards Flashcards
(32 cards)
what does weather mean
day to day conditions of atmosphere, involiving temperature, precipitation and wind.
what does climate mean
average weather conditions recorded over a period for at least 30 years.
what happens to temperature further away from equator
gets cooler
what happens to temperatures closer to equator
gets warmer, closer to solar radiation
why does coastline reduce temperature
sea winds
what factors affect climate
latitude, altitude, wind ocean currennts, continentality
atmosphere
air above us containing co2, o2, water vapour etc.
circulation
circular air movements called cells that join together to form the overall circulation of the Earth’s atmosphere.
what type of air pressure occurs when the air is sinking
high pressure
what type of air pressure occurs when the air is rising
low pressure
how does wind travel
direction of high air pressure to low air pressure, balancing out variations in air pressure which is why it has a direction.
where does high pressure occur
dry stable conditions
where does low pressure occur
wet unstable conditions
why is there low air pressure on the equator
- suns light concentrated over small area around equator
- therefore thermal insolation greatest at equator
- air therefore rises at equator creating low air pressure
what does ITCZ stand for
Inter Tropical Convergence Zone
how does the low pressure around equator create the ITCZ
low pressure characterized by heavy rain, thunderstorms as warm air can carry more moisture and rises to form clouds at the equator. this zone is called ITCZ
how is the Hadley Cell formed
- rising air from ITCZ moves laterally towards poles.
- air eventually cools as recieves less thermal insolation and descends causing high pressure.
- characterises dry conditions of areas such as sahara
- falling air rushes to adjacent areas of low pressure such as equator to balance out air pressure, resulting in trade winds.
- this circular process completes the Hadley Cell
- repeats further north and south to form Ferrel and Polar cells
natural hazard
extreme natural event or process that can lead to loss of life and or extreme damage to property and severely disrupts human activity.
what type of cells are the hadley, ferrel and polar cell
convection cells
what happens to the air at the equator
The Earth’s surface is warmed by the Sun at the equator and transmits this heat to the nearby air which gets hotter and rises. The rising, hot air forms a low-pressure belt. As the hot air rises, the air will begin to cool, with water vapour condensing, creating rain and clouds.
The rising air cools and moves away from the equator towards 30 degrees north and south.
what happens at 30 degrees north and south
At 30 degrees north and south, the air is further from the equator and the cool air falls resulting in a high-pressure belt with minimal rainfall and no clouds.
When the cool air reaches the Earth’s surface, surface winds blow the cool air either towards the equator, or away from the equator towards the Poles
what happens at 60 degrees north and south
At 60 degrees north and south, cold air blown from the poles meets warm air surface winds. Because the warmer air is less dense, it rises and forms a low-pressure belt.
The air splits, with some returning back towards the equator and the rest heading to the poles.
what happens at the poles
At the North Pole and the South Pole, cool air will sink, forming a high-pressure belt.
This high-pressure belt will move back towards the Earth’s equator as a surface wind.
global patterns of temperatures
average global temperature 20C-28C exreme countries away from equator 10C,-10C
