Urban microclimates Flashcards
What is Albedo?
The amount of solar radiation reflected back into the atmosphere from a surface or material.
What is Anthropogenic Heat?
Atmospheric heat generated by human activity.
Define Rural Boundary Layer (RBL).
The layer of atmosphere in contact with the Earth’s surface outside the city boundary.
What is Urban Boundary Layer (UBL)?
The layer of atmosphere in contact with or influenced by the height of the built-up environment within the city.
Define Urban Canopy Layer (UCL).
The layer of the atmosphere below the height level of buildings in the city.
What is Urban Canyoning?
An increase in wind speed due to the restriction of airflow within closed narrow streets.
What is Urban Plume?
The extension of the Urban Boundary Layer downwind of the city boundary.
What does Urban Heat Island Effect (UHIE) refer to?
The process by which the metropolitan area becomes significantly warmer than the surrounding countryside.
True or False: UHIE affects all cities equally.
False.
In which climate zones is UHIE most pronounced?
Temperate climate zones away from the modifying influence of the coast.
What are isotherms?
Lines that connect equal points of temperature.
What is the effect of albedo and heat capacity on urban temperature?
Concrete and dark glass surfaces have lower albedo and absorb more solar radiation, leading to warmer temperatures.
How does evapotranspiration affect urban temperatures?
Lower rates of evapotranspiration lead to warmer temperatures in cities.
When is UHIE most evident during the day?
After 16:00 hrs.
What is the relationship between Urban Boundary Layer (UBL) and precipitation?
UBL acts as a barrier that deflects airflow upwards, increasing cloud cover and potential rainfall.
What causes photochemical smog?
Sunlight reacts with nitrogen oxides and at least one volatile organic compound (VOC) in the atmosphere.
What is a key factor that concentrates pollutants in photochemical smog?
Temperature inversion.
What is the main focus of managing Urban Heat Island Effect (UHIE)?
Green and blue urban planning.
Fill in the blank: Soft Screening creates ‘urban lungs’ that filter the air by trapping _______.
PM2.5 and PM10.
What is the main way to improve air quality in urban areas?
Reduce the source of pollution.
What are some strategies to reduce urban air pollution?
Improved government regulation, reducing polluting vehicles, and investing in public transport.
What impact do cities have on wind patterns?
Cities experience weaker wind patterns due to UBL and can have micro-scale variations caused by urban planning.
What is the Venturi Effect?
The process of increased wind speed through a combination of restricted airflow and a drop in air pressure.
What are some characteristics of photochemical smog formation conditions?
High air pressure and calm wind conditions.
What is a significant issue regarding urban air quality according to the WHO?
More than 80% of people in urban areas are exposed to air quality levels exceeding WHO limits.
What percentage of cities in low- and middle-income countries do not meet WHO air quality guidelines?
98%.
What is the effect of tree cover on busy roads in urban areas?
It can disturb airflow, creating pollution hotspots.
What are some methods to manage urban energy and water demands?
Increase renewable power supply, reduce reliance on fossil fuels, and implement recycled and grey water schemes.
