Chapter 3 - Weather Hazards Flashcards
What’s global atmospheric circulation
Helps to explain the location of world climate zones and the distribution of weather hazards
What’s the most important influence on worldwide variations in climate/ tell me about how sunlight affects the climate
Latitude, because the curved surface of the earth, the equator receives much higher insolation that the polar latitudes - where’s as at low latitudes, sunlight is more highly concentrated
As a result, air at the equator is heated strongly - it becomes less dense and rises to high altitude, this creates a global climate zone of low pressure, the equatorial zone
After rising, the air spreads out and begins to flow towards the north and south poles
In low insolation received at polar latitudes result in colder, dense air and high pressure
As the air sinks towards ground level, it spreads out and flows towards the equator
What’s a convection cell
The low pressure belt at the equator and the high pressure belt at the poles provides the basis for a simple convection cell to operate
What’s the Hadley cell
The areas of high pressure at the tropics of cancer and Capricorn, air sinks towards the ground there and as it descends the air warms. The result is high pressure and hot, dry desert conditions. This circulation of air between the tropics and equator is the Hadley cell
What’s global circulations
Involves 3 cells Becuase the earth rotates on its axis , the movement generates strong, high altitude winds which wrap around the planet like belts
These winds flow towards the east, as the earth spins and interact with the convection cells.
What are jet streams
Strong high altitude currents of air
What are the global convection cells
Polar cell, Ferrel cell, Hadley cell
How is precipitation influenced by global pressure and surface winds at the equator
Rainfall is high and constant throughout the year near the equator. As hot air rises, it cools slightly. Water vapour is converted into droplets of conventional rain
How is the intertropical convergence zones precipitation affected by global pressure and surface winds
It’s a low pressure zone, air rises and triggers bursts of torrential rain. Sometimes the area grows a wave of low pressure which extends further than usual. Tropical storms develop along these waves. Once they gain energy, they can travel even further away from the equator
How is rainfall affected by coastal areas in Europe by global pressure and surface winds
Rainfall often higher due to movement of the jet stream over Atlantic. Rain bearing weather systems called depressions or cyclones follow the jet stream, often bringing stormy conditions to the uks west coast
How is rainfall affected in the tropics by global pressure and surface winds
Rainfall is often low around the tropics of Capricorn and cancer. Dry air descends there as part of the Hadley cell, resulting in arid conditions
Tell me how rainfall is affected in the polar regions by global pressure and surface winds
Precipitation is low in polar regions and mainly falls as snow. The cold air has a limited ability to hold water vapour
What are tropical storms
Are a natural hazard
Occurs when warm air rises to create an area of intense low pressure, much lower than depressions experienced in the U.K.. As the warm moist air reaches high altitudes, powerful winds spiral around the calm central point , creating the “eye of the storm” and the warm air cools and condenses into heavy rainfall and thunderstorms
How are names of tropical storms made
They are alphabetical and alternate in gender, more recognisable and engaging for public when given names rather than coordinates. Names repeat every 6 years unless a large loss of life or cost In damage would make it insensitive to repeat it
What are tropical storms called
They are called differently deepening on their location
Hurricanes in Atlantic and eastern Pacific oceans
Typhoons in the west of the North Pacific Ocean
Cyclones in the Indian and South Pacific oceans
Where do tropical storms occur
In the tropics where the intertropical convergence zone is - broadly south of the tropic or cancer and north of the Tropic of Capricorn
Found in areas of low latitude - between 5 and 30 degrees north and south of equator
Here a higher insolation means temperatures are higher than at the poles
Tell me the conditions for a tropical storm to form
Sea must be about 27 C and a depth of 60-70 Metres
This provides the heat and moisture that causes the warm air to rise Rapids in this low pressure region. Latent heat is then released which powers the tropical storm . The warmest seasons are between summer and autumn which is most typical for tropical to develop
There is low wind shear (which remains constant and does not vary with height) so that the tropical storm clouds can rise to high levels without being torn apart
They don’t develop on along the equator because the Coriolis effect is not strong enough here for strong tropical storms to spin
How does a tropical storm form
Air is heated above the surface of warm tropical oceans, the warm air rises rapidly under the low pressure conditions
The rising air draw up more air and large volumes of moisture from the ocean, causing strong winds
The Coriolis effect causes the air to spin upwards around a calm central eye of the storm
As the air rises, it cools and condenses to form large, towering cumulonimbus clouds which generate torrential rainfall. The heat given off when the air cool powers the tropical storm
Cold air sinks in the eye, therefore there is no cloud, so it’s drier and much calmer
The tropical storm travels across the ocean in the prevailing wind
When the tropical storm meets land it is no longer fuelled by the source of moisture and heat from the ocean and so it loses power and weaken, the air pressure and temperature rise. Wind and rainfall subside
Why does a tropical storm spin
The Coriolis effect bends and spins the warm rising air.
Hurricanes in the northern hemisphere bend to the right, which causes the clouds to swirl anti clockwise whereas cyclones in the Southern Hemisphere swirl In a clockwise direction
What direction do tropical storms travel
Travel from east to west due to the direction the earth spins
When they hit land, they lose their energy source from the sea that powered them - friction also allows them to slow down and as they slow doe they change direction
How long does an average tropical storm live for
1-2 weeks
What is the Coriolis effects
Wind blows from areas of high pressure to areas of low pressure, as the earth rotates it causes wind to bend because the earths curvature and so the earth spins faster at the equator and difference in speed means that wind bends as it blows across the earth
How could climate change alter the conditions that cause tropical storms to formed
As the temperature increases, sea levels will rise due to thermal expansion. The impact of rising sea levels will mean storm surges are expected to become higher
A Warmer atmosphere will mean the air can hold more moisture. So heavy rainfall is expected to increase. Therefore flooding during a tropical storm would be more destructive
How does climate change affect the intensity of tropical storms
There is evidence of warmer oceans and the intensity of tropical storms - and expected to become more severe
Every 1 C increase in sea surface temperatures will mean a 3-5 percent increase in wind speed
How does climate change affect the frequency and distribution of tropical storms
Frequency to stay same or decrease
By will be more severe storms, and category 1-3 storms will decrease
The regions where tropical storms are experienced are not expected to change significantly as a result of climate change
How does the uncertainty of tropical storms change due to climate change
Predicting impacts is unreliable as the rate of and impact of climate change in the future is uncertain
Potential risk to like and property has already increased due to population growth and building in coastal locations even without factoring in climate change
