Urban Climates

Question 1

What is weather? What is climate? - Urban Climates

Answer 1

Weather is the day to day atmospheric conditions in a particular area. Climate is the average weather conditions of a place.

Question 2

What are urban climates? - Urban Climates

Answer 2

Urban climates are a set of climactic conditions that prevail in a large metropolitan area which differ from the climate of rural surroundings.

Question 3

What are the 7 elements of weather? - Urban Climates

Answer 3

Temperature, precipitation, cloud, wind, air pressure, humidity and sunshine.

Question 4

What are climatic domes? What 2 sections can climatic domes be divided into? - Urban Climates

Answer 4

Climatic domes are areas of distinctive climactic conditions. Climatic domes can be divided into URBAN CANOPIES, where conditions act in space between buildings, and URBAN BOUNDARY LAYERS, which is the area encompassing the conditions present in urban areas and downwind rural areas.

Question 5

What is an albedo? What surfaces have high/low albedos and what are the consequences of this? - Urban Climates

Answer 5

An albedo is the reflective qualities of an object. White surfaces have high albedos while dark surfaces have lower albedos. Low albedo surfaces can absorb thermal energy and radiate it to their surroundings, whereas high albedo surfaces generally reflect it away from urban areas.

Question 6

Why do urban areas largely have lower albedos then rural areas? - Urban Climates

Answer 6

Urban areas have many buildings and road surfaces composed of dark surfaces, meaning that they have lower albedos than rural areas which lack these surfaces.

Question 7

What is an urban heat island? - Urban Climates

Answer 7

An urban heat island is an urban area that is significantly warmer than its rural surroundings as a result of human activities.

Question 8

What factors contribute to urban heat islands? (3) - Urban Climates

Answer 8

Pollution from cars and factories increase cloud cover due to condensation nuclei increase, entrapping outgoing solar radiation beneath clouds. Human activity produces heat (cars, factories, heating, refrigeration, AC), increasing urban temperatures. Reduced evapotranspiration means that thermal energy is not used to conduct these processes, raising temperatures.

Question 9

Why is the urban heat island effect higher at night? - Urban Climates

Answer 9

The urban heat island effect is higher at night as surfaces and objects continue to radiate heat that has been absorbed during the day. This means that urban areas do not cool as much as rural areas when temperatures fall at night.

Question 10

Why is the urban heat island effect stronger in summer? - Urban Climates

Answer 10

The urban heat island effect is stronger in summer due to the presence of increased solar radiation, meaning that due to lower albedos, urban areas absorb more thermal energy than rural areas.

Question 11

Why is the urban heat island effect stronger in high pressure systems? - Urban Climates

Answer 11

The urban heat island effect is stronger in high pressure systems as there are fewer clouds, allowing more solar radiation to reach and heat the ground. Low winds mean that warm air is not dispersed.

Question 12

What are temperature plateaus/cliffs/peaks? Why do they emerge? - Urban Climates

Answer 12

Temperature plateaus are where the temperature remains similar over a certain section of an urban area. Temperature cliffs are where temperatures rapidly increase/decrease in an urban area. Temperature peaks are the highest temperatures in an urban area. Plateaus exist in areas of similar building type, cliffs/sinks exist in areas of changing land use.

Question 13

Where in cities do pockets of cool air emerge? Why? What is this known as? - Urban Climates

Answer 13

Pockets of cool air emerge in green areas/bodies of water in cities due to evapotranspiration absorbing thermal energy, the increased albedo of these areas and the reduced ability to absorb thermal energy. These are known as temperature sinks.

Question 14

Why does it rain more in urban areas than rural areas? (4) - Urban Climates

Answer 14

Warm air holds more water, and as warm air rises it forms clouds, urban areas have lower pressure due to rising air, more water vapour is produced from industry and power stations, dust and pollution from urban areas act as condensation nuclei.

Question 15

Why are thunderstorms more common in urban areas than rural areas? - Urban Climates

Answer 15

Thunderstorms can be generated by rising heat and water vapour created from power stations and pollution. Clouds are increased due to the increased presence of condensation nuclei.

Question 16

Why is fog more common in urban areas than rural areas? What can be said about the nature of urban fog? - Urban Climates

Answer 16

Fog frequency is greatly increased in urban areas due to there being more condensation nuclei from human activity and industry. Urban fog is also of increased intensity and length.

Question 17

Why is cloud cover more common in urban areas than rural areas? - Urban Climates

Answer 17

Cloud cover is increased in urban areas due to the high concentration of condensation nuclei, low pressure causes cloudy conditions, buildings can cause vertical uplift.

Question 18

Why are there fewer frosts in urban areas compared to rural areas? - Urban Climates

Answer 18

Urban areas have fewer frosts due to the urban heat island effect, which means that urban areas tend to be warmer as a result of radiating their own thermal energy and absorbing more thermal energy than rural areas do.

Question 19

What is channelling? What is the Venturi Effect? - Urban Climates

Answer 19

Channelling is when wine is directed down canyon-like streets due to reduced friction. The Venturi Effect is when wind is squeezed into increasingly narrow gaps, causing a pressure decrease and velocity increase.

Question 20

Why is average wind speed usually lower in urban areas than rural areas? - Urban Climates

Answer 20

Urban areas usually have lower wind speeds than rural areas due to the fact that rough-sided buildings create friction and slow down wind speeds, something which does not occur in rural areas.

Question 21

How is wind direction different in urban areas compared to rural areas? - Urban Climates

Answer 21

Urban wind direction is usually determined by the position and height of buildings in relation to each other. This is different from rural areas, where it is effectively solely determined by the movement of air from high to low pressure.

Question 22

What is turbulence? How does turbulence impact urban wind speeds? - Urban Climates

Answer 22

Turbulence is a rapid and abrupt change in wind direction and speed. Turbulence impacts urban wind speeds due to the fact that when wind impacts upon a building, it can deflect gusts downwards, upwards or even slow the wind.

Question 23

What is eddying? How does it operate? - Urban Climates

Answer 23

Eddying is the circular movement of wind gusts caused by differences in pressure. When a wind impacts a building, this causes high pressure at that building, while buildings opposite exist in a low-pressure environment. This causes the wind to swirl towards that side, creating a spiralling movement of winds.

Question 24

How can the spacing of buildings impact the wind? (Widely vs Closely) - Urban Climates

Answer 24

Widely spaced buildings result in minimal eddying of winds, allowing winds to move upwards and downwards around them. Closely spaced buildings can create swirling, circular wind directions between buildings, while winds can also skim over the top of these buildings rather than dropping between them.

Question 25

What is the channelling effect? What impacts does the channelling effect have on construction and urban planning? - Urban Climates

Answer 25

The channelling effect is where winds are directed down long and narrow streets. The channelling effect can cause the swaying of buildings or impacts on pedestrians, meaning that planning of buildings can be influenced to reduce extreme wind strengths.

Question 26

How can the urban heat island effect impact winds in urban areas? - Urban Climates

Answer 26

Conventional uplift in urban areas creates low pressure, whereas in rural areas pressure is higher. When winds occur in rural areas with high pressure, pressure gradients result in the winds being drawn in to urban areas.

Question 27

What are cyclonic conditions? What are anti-cyclonic conditions? - Urban Climates

Answer 27

Cyclonic conditions are the conditions resulting from low pressure environments. LOUSY WEATHER.
Anti-cyclonic conditions are conditions resulting from high pressure environments. HAPPY WEATHER.

Question 28

Describe the quality of air in urban areas. What contributes to this? - Urban Climates

Answer 28

Urban areas tend to have poorer air quality than rural areas, caused by dust, soot, gases from vehicles and industry.

Question 29

What are the sources of carbon monoxide? What are the impacts of this form of pollution? - Urban Climates

Answer 29

Carbon monoxide is caused by vehicular pollution, usually created by catalytic converters. This results in headaches, sickness, coughing, fatigue, nausea. Restricts transport of CO2 around the body.

Question 30

What are the sources of sulfur dioxide? What are the impacts of this form of pollution? - Urban Climates

Answer 30

Sulfur dioxide is produced by power generation/industry. This results in coughing, smog and acid rain.

Question 31

What are the sources of nitrogen dioxide? What are the impacts of this type of pollution? - Urban Climates

Answer 31

Nitrogen dioxide is produced by traffic and transport emissions. Road transport is responsible for 50% of NO2 emissions. This can cause pulmonary damage and acid rain.

Question 32

What are the sources of particulate matter? What are the impacts of this form of pollution? - Urban Climates

Answer 32

Particulate matter is produced by quarrying, industry, vehicle exhausts, mould and pollen. This results in pulmonary damage, creates condensation nuclei and causes increased cloud cover. Can create heart disease and asthma.

Question 33

What is smog? When has it had a major impact in the UK? - Urban Climates

Answer 33

Smog is a mixture of smoke and fog common in cities throughout the 19th, 20th and 21st centuries due to industrialisation. The 1952 London Great Smog contributed to 4000 deaths as a result of anti-cyclonic conditions creating intense smog.

Question 34

What is photochemical smog? In what (specific) cities is this a problem and why? - Urban Climates

Answer 34

Photochemical smog is when pollutants come into contact with sunlight, with UV light breaking these pollutants down into harmful chemicals which form photochemical smog. This is a problem in cities such as Beijing, LA and Mexico City due to their hot and sunny conditions.

Question 35

What are the impacts of photochemical smog? - Urban Climates

Answer 35

Photochemical smog can result in breathing difficulty, headaches, nausea and respiratory disorders.

Question 36

Describe what happens during a temperature inversion. What are the impacts of this? - Urban Climates

Answer 36

A temperature inversion sees warm, moist air forming atop cold surface air. This moist air is entrapped by cold, sinking air above it. The presence of this warm air between 2 bands of cold air entraps pollutants beneath it, resulting in poor air quality.

Question 37

What happens during vehicle control policies? Name an example of these - Urban Climates

Answer 37

People are charged for using their vehicles in certain places/at certain times, reducing road traffic and the production of particulate matter/CO/NO2.
Seen in London’s Congestion Charge and Mexico City’s aims to restrict cars to certain days.

Question 38

What happens during zoning of industry policies? (2) - Urban Climates

Answer 38

Zoning of industry policies see industry located downwind from cities, meaning that pollutants cannot linger over an urban area. Furthermore, planning legislation can force companies to build chimneys to release pollutants above the inversion layer. This improves urban air quality.

Question 39

What are the results of vehicle emissions legislation? Name an example of these - Urban Climates

Answer 39

Government targets and laws can result in the forced introduction of low emission cars or the preventing of sales of diesel/petrol cars. This can be seen through Government plans to ban sale of petrol/diesel cars by 2030.

Question 40

What are the results of public transport schemes? Name an example of these - Urban Climates

Answer 40

Public transport schemes can improve introduction of trains and buses to reduce the emissions created from personal cars. Park and Ride Schemes in York, Santander Bikes in London.

Question 41

What are the results of atmospheric measure policies? Name an example of these - Urban Climates

Answer 41

Restrict and prevent the emission of pollutants into the atmosphere through policies and plans to place the responsibility to reduce emissions on companies and individuals.
1956/68 Clean Air Acts have introduced smoke control areas, MOT tests reduce emissions, London has its ULEZ.

Question 42

What are the results of alternative fuel use? - Urban Climates

Answer 42

Petrol and diesel have been replaced with less polluting fuels such as biofuels or electricity, liquified petroleum has reduced emissions.

Question 43

What are the advantages and disadvantages of vehicle control policies? - Urban Climates

Answer 43

Advantages: congestion charges in London have reduced traffic and emissions within the congestion zone, increased public transport use.
Disadvantages: some people navigate around the edges of congestion charge zones, increasing the emissions produced, difficult to process fines due to high traffic volumes.

Question 44

What are the advantages and disadvantages of the zoning of industry? - Urban Climates

Answer 44

Advantages: can prevent poor visibility and air quality in cities.
Disadvantages: cannot be applied retrospectively if industry is already placed in the centre of urban areas.

Question 45

What are the advantages and disadvantages of vehicle emission legislation? - Urban Climates

Answer 45

Advantages: fossil fuel combustion and particulate matter presence reduced as result of lower use of diesel cars, reduces reliance on fossil fuels,
Disadvantages: electric cars expensive and unaffordable, lacking in sufficient infrastructure to charge cars.

Question 46

What are the advantages and disadvantages of public transport schemes? - Urban Climates

Answer 46

Advantages: links city to suburbs, incredibly successful, reduces emissions in event of major uptake.
Disadvantages: unattractive to some prospective users.

Question 47

What are the advantages and disadvantages of atmospheric measure policies? - Urban Climates

Answer 47

Advantages: place a legally binding onus on businesses and groups to reduce their emissions, can provide strict regulation and mitigation.
Disadvantages: can often be ineffective or difficult to enforce, can be difficult to be applied retrospectively.

Question 48

What are the advantages and disadvantages of using alternative fuels? - Urban Climate

Answer 48

Advantages: reduces the use of coal, petrol and diesel, some of the most potent and damaging sources of pollutants.
Disadvantages: can promote monoculture and deforestation in the instance of biofuels, electric cars often inaccessible.