Weather and Climate : UHI

?
what is an urban heat island?
The area above and around a city where air temperatures are greater than the surrounding rural air temperatures
1 of 30
What is the annual mean temp for cities in comparison to rural areas
0.5-0.8C warmer. In winter this increases to 1-1.5C as people put on central heating,
2 of 30
what are 4 things that affect temperature in a city?
Tarmac (absorbs insolation and then conducts heat), Traffic (pollution from CO2/heat from exhausts), Building materials (glass reflects heat back down and dark coloured buildings absorb insolation), heat emitted from buildings
3 of 30
The bigger the city the ___ the UHI. The more developed the city the ____ the UHI.
The bigger the city the greater the UHI. The more developed the city the less pollution is emits, so the smaller the UHI.
4 of 30
What effect does the Thames have?
In london it may have a slight cooling effect, particularly in East London as the river is wider here.
5 of 30
How much precipitation is there in cities in comparison to rural areas?
5-10% more
6 of 30
Describe the effect of convectional rainfall in urban areas
An industrialising city such as new Delhi will have a greater UHI and thus more convectional rainfall.
7 of 30
Describe the effect of water vapour in urban areas
Although there is little difference in the amount of water vapour that cities and rural areas retain in their atmosphere, the higher urban temperatures effectively lower its relative humidity. urban areas have the greater potential to hold water.
8 of 30
Describe the effect of vertical movement of air in urban areas
An orographic effect can be created as buildings force air to rise, creating a form of relief rainfall. eg tokyo.
9 of 30
Describe the effect of condensation nuclei in urban areas
CN are made form vehicle exhausts and industry. In an industrialising city there are more, and so there is more rain. Water molecules condense onto CN, forming clouds, although they can be naturally occurring particles such as sand.
10 of 30
How do vortices affect wind in an urban area?
The more buildings, the more turbulence, particulalry if the area is high density. the taller the building the larger the vortices.
11 of 30
How does pressure affect wind in an urban area?
The UHI creates rising air, which creates relative low pressure. the pressure gradient draws air in, so the outer suburbs get more wind. this effect increases alongside the UHI.
12 of 30
How does the canyon effect affect wind in an urban area?
An example of the venturi effect, winds are squeezed into increasingly restricted streets, creating a pressure gradient and therefore increasing wind speeds. A greater canyon effect is created in a grid plan city eg manhattan in NYC.
13 of 30
list the 4 pollutions in cities
sulphur dioxide, nitrogen oxides, carbon monoxide, particulate matter
14 of 30
Describe sulphur dioxide
A respiratory irritant associated with the onset of asthma. Produced by burning fossil fuels. coal fired power plants are the worst SO2 polluters.
15 of 30
What was done to stop SO2 production
In the 80's, coal mines in the UK were shut down, switching the country from coal to gas as the primary energy source.
16 of 30
__% of childhood asthma is due to ______, costing the US $____ per year.
30% of childhood asthma is due to environmental exposure, costing the US $2 billion per year.
17 of 30
describe nitrogen oxides
increases respiratory problems such as coughing and bronchitis. Primary source is the burning of fossil fuels.
18 of 30
What can be done to stop NOx production
Reducing car use and traffic.
19 of 30
In UK cities __% of NOx comes from motor vehicle exhaust
In UK cities 50% of NOx comes from motor vehicle exhaust
20 of 30
Describe carbon monoxide
colourless odourless gas produced by incomplete or inefficient combustion of fuel. The gas is poisonous, affecting the transport of blood around the body, reducing oxygen to the muscles and organs. restricted blood flow and cardiovascular problems
21 of 30
Road transport is responsible for __% of all CO emissions in the UK
Road transport is responsible for 90% of all CO emissions in the UK
22 of 30
In the year proceeding the Beijing Olympics (2007-2008), China cut traffic in Beijing, temporarily reducing CO by __%
70%
23 of 30
describe particulate matter
form condensation nuclei. PM 2.5 is the most damaging as it is the smallest and can penetrate furthest into the body. Increases risk of heart attack. Can be cut down through cleaner air targets
24 of 30
How many people die annually as a direct result of air pollution via asthma, lung disease and cancer?
30,000 in the UK
25 of 30
The EU clean air targets are currently ___ what the WHO recommends
The EU clean air targets are currently double what the WHO recommends
26 of 30
How can pollutant domes affect city climate?
They can absorb long wave and short wave radiation, creating almost exponential temperatures.
27 of 30
What is photochemical smog
A form of air pollution that occurs in cities. Exhuast fumes become trapped by temperature inversion associated with anticyclones which contain the pollution dome. Formed by NOx. low level ozone is created from the sun breaking down nitrogen oxide.
28 of 30
How does topography affect photochemical smog?
For example, LA sits in a basin and so smog forms more readily as pollution is not swept away buy winds and can be easily trapped in a temperature inversion.
29 of 30
How can smog have a cooling effect
As sunlight cannot reach the surface.
30 of 30

Other cards in this set

Card 2

Front

What is the annual mean temp for cities in comparison to rural areas

Back

0.5-0.8C warmer. In winter this increases to 1-1.5C as people put on central heating,

Card 3

Front

what are 4 things that affect temperature in a city?

Back

Preview of the front of card 3

Card 4

Front

The bigger the city the ___ the UHI. The more developed the city the ____ the UHI.

Back

Preview of the front of card 4

Card 5

Front

What effect does the Thames have?

Back

Preview of the front of card 5
View more cards

Comments

No comments have yet been made

Similar Geography resources:

See all Geography resources »See all Weather systems resources »