CUE - Urban Climate

Question 1

What is the urban climatic dome?

Answer 1

The urban area within which the climate and weather is different from that of the surrounding rural areas in terms of temperature, relative humidity, precipitation, visibility, air quality and wind speed.

Question 2

Urban weather has less…

Answer 2

sunshine duration
occurrence of frosts
relative humidity in winter
relative humidity in summer
snowy days

Question 3

Urban weather has more

Answer 3

total precipitation
rainy days
annual mean temp
winter max temp
cloud cover
occurrence of fog
condensation nuclei

Question 4

What is the urban canopy?

Answer 4

The urban canopy is the layer of air closest to the surface in the cities, extending upwards to mean building height, where processes act in the spaces between buildings.

Question 5

What is the urban boundary layer?

Answer 5

The layer above the urban canopy, that forms a dome of warmer air that extends downwind and, at height, as a plume into surrounding rural areas.

Question 6

How do urban surfaces have different albedos than rural areas?

Answer 6

In urban areas there are more dark surfaces such as pavements and roofs, which have a very low albedo. In addition, there are many highly reflective buildings made from glass which have very high albedos but reflect the heat back onto the ground and into the city.

Question 7

4 reasons why temperatures fluctuate in urban areas

Answer 7

season
weather conditions
sun intensity
ground cover

Question 8

4 causes of the urban heat island

Answer 8

albedo - building materials have low albedo so absorb heat in day and release at night, large windows concentrate heating effect into surrounding streets by reflecting energy downwards
air pollution - industries and vehicles, increases cloud cover and creates pollution dome
urban moisture and heat budget - water falling on surface disposed of asap, reducing evapotranspiration, more energy can heat atmosphere
industry and people - industries, buildings vehicles burn fuel. air conditioning units release hot air to atmosphere. people generate heat

Question 9

Issue with the urban heat island: as temperatures rise in the summer months…

Answer 9

Conditions in buildings and on city transport systems can become uncomfortable. Increases cases of heat stroke, asthma, organ damage and death. Babies and elderly are most likely to be affected.

Question 10

Issue with the urban heat island: Hot and still anticyclonic weather conditions responsible for intensive urban heat island events…

Answer 10

Also produce higher air pollution levels.

Question 11

Issue with the urban heat island: prolonged survival and high reproduction rates of…

Answer 11

Some animal and insect pests can be a problem. There is greater potential of algal blooms in water courses.

Question 12

Issue with the urban heat island: earlier flowering times of…

Answer 12

plants and trees in cities and a prolonged growing season may cause discomfort for city residents due to a longer allergy season.

Question 13

Issue with the urban heat island: increased water consumption…

Answer 13

by residents and businesses places extra strain on the water supply infrastructure and can lead to water use restrictions.

Question 14

Issue with the urban heat island: excessive heat puts…

Answer 14

an increased strain on the supply of energy for cooling and air conditioning.

Question 15

Issue with the urban heat island: climate change…

Answer 15

is expected to increase the intensity of the urban heat island effect in most urban areas.

Question 16

Issue with the urban heat island: an increased risk of the deterioration…

Answer 16

of historical monuments and buildings through increased rates of temperature related chemical weathering.

Question 17

Strategies to address the issues with the urban heat island: cool surfaces

Answer 17

roofs built from materials with high albedo absorb and store less solar energy during the day, so emit less heat at night.

Question 18

Strategies to address the issues with the urban heat island: green roofs

Answer 18

reduce rooftop temperatures by up to 20-40 degrees. reduce rainwater runoff, act as insulators and increase urban biodiversity.

Question 19

Strategies to address the issues with the urban heat island: urban greening

Answer 19

planting trees and vegetation provides shade and can have a natural cooling effect. they also act as carbon stores, can reduce urban flooding and filter pollutants from the air.

Question 20

Strategies to address the issues with the urban heat island: sky view factor

Answer 20

the openness between buildings in an urban area. a restricted sky view reduces the escape of heat from street and building surfaces, contributing to heat within street canyons.

Question 21

Strategies to address the issues with the urban heat island: cool cars

Answer 21

a lighter coloured car reflects more sunlight than a traditional dark car. this cools the inside of the car and reduced the need for air conditioning.

Question 22

Causes of photochemical smog

Answer 22

2 main causes are vehicles and industry

• most likely in anticyclonic conditions: high pressure system, dry, little wind or cloud
• also when temperature inversions occur (cold air trapped under warm): e.g in LA (where there’s a basin)
• pollutants are trapped
• sunlight reacts with pollutants (e.g nitrogen oxides)

Question 23

Where does carbon monoxide mainly come from?

Answer 23

road transport

Question 24

What causes nitrogen dioxide?

Answer 24

road transport (50%)

Question 25

Where do particulates mainly come from?

Answer 25

Power stations and vehicle exhausts

Question 26

Source of sulphur dioxide

Answer 26

industry e.g power stations

Question 27

Impact of carbon monoxide

Answer 27

affects the transport of oxygen around the body

breathing in low levels can result in: headaches, fatigue, nausea

Question 28

Impact of nitrogen dioxide

Answer 28

can inflame the lining of the lung - worse for people who suffer from asthma
oxidation of this can also cause weathering of buildings

Question 29

Impact of particulates

Answer 29

health problems for the airway and lungs

Question 30

Impact of sulphur dioxide

Answer 30

coughing tightening of chest and narrowing of airways

can also produce haze, acid rain, damage to plants and buildings