weather - natural hazards Flashcards
storms, global atmospheric circulation
What does global atmospheric circulation mean?
movement of air across the earth in a specific pattern driven by the difference in heat on the earth’s surface
what are the 3 types of cell
polar, ferrel, hadley
where is the hadley cell
from the equator to the 30° latitude line
sequence of the hadley cell
-air separates & move north & south
-reaches 30° and sinks, subtropical high p
-completes cycle, flows back towards equator as trade winds
what are the trade winds in north
northeast trade winds
what are the trade winds in south
southwest trade winds
what are the different directions of trade winds caused by
the Coriolis effect
where is the ferrel cell
between 30° and 60°
sequence of the ferrel cell
-air is pulled towards the poles, forming warm southwesterly winds in north, northwesterly in the south
-gain moisture, at 60° meet cold air
-warm air from tropics is lighter than polar air so rises
-uplift causes low p, unstable weather with mid-latitude depression
where is the polar cell
60° to poles
sequence of polar cell
-poles, air is cooled and sinks forming high pressure, this is the Polar high.
-It flows towards the lower latitudes
-At 60° N and S, polar air mixes with tropical air and rises, creating low pressure called the subpolar low.
The boundary between the warm and cold air is called the polar front. It accounts for a great deal of the unstable weather experienced in these latitudes.
what is a tropical storm
intense low pressure weather system that can last days-weeks within tropical regions
what are tropical storms also known as
hurricanes, cyclones, typhoons
5 conditions needed for tropical storms to form
-between 5-30° North + South of equator
-sea temperature >27°C for 60-70m deep
-warmest season
-low wind shear
-not on equator
sequence of tropical storm formation
1.Warm air rises from the ocean as it rises it leaves a space below it (low pressure). This space is instantly filled by surrounding air ,rushing in causing strong winds.
2.The air that rushed in warms up and rises too. This rising air brings moisture. This cools and condenses to form storm clouds (eye wall)
3.When the cooled air descends it forms an area of calm in the centre (eye)
4.Due to the winds near the equator, storm starts to move from east to west. Earth’s spin causes winds to curve and makes storm spin.
where do tropical storms form and what direction do they travel
over warm oceans, travel from east to west
what’s the Coriolis effect
winds don’t blow in straight lines due to the earth’s rotation; the difference in speed at equator means winds blow
3 primary impacts of tropical storms
-strong winds (at least 119km/h)
-torrential rainfall (up to 500ml in 24hrs)
-storm surges (up to 5m)
6 secondary impacts of tropical storms
-houses demolished
-infrastructure + crops destroyed
-aid hampered
-landslides
-contamination of water supplies
-flooding
how will climate change affect tropical storms
higher intensity and possibly higher frequency due to more areas warm enough for their formation but not enough evidence
how to monitor tropical storms
satellites - cloud patterns associated with storms
aircrafts - can collect data on air pressure, rainfall, wind speed
how to predict tropical storms
supercomputers can give 5 days warning
track cones
how to protect from tropical storms (6)
storm shutters on windows, tie down windborne objects, install emergency generator + hurricane straps, reinforce doors, remove trees close to buildings
how to plan for tropical storms (5)
educate, advise, government plans, storm shelters, building regulations
what is a storm event
weather system that is severe, unusual, or unexpected, and can cause damage or threaten life
why does the UK regularly experience storms and weather depressions
due to its location, the jet stream, and the Polar Front
what are the 4 types of flooding in the UK
-river flash flooding
-coastal flooding
-slow onset flooding
-surface water flooding5
what weather hazards affect the UK
storm events, wind, snow, droughts and heatwaves
drought definition
extended period of low/no rainfall relative to expected average for the region
