Microclimates Chapter 15, pg. 252-256 1. Explain exposure: Refers to the influence of wind on temperature and humidity. Exposure to direct sunlight – affects on micro level 2. What is wind chill? Strong winds that reduce temperatures. Ex. A mountain slope that faces prevailing winds is often much colder than one that is sheltered. Refers to how cold the temperature feels to people because of the wind. It does not actually lower the temperature. 3. Explain albedo: Relates to how surfaces convert solar energy into heat. Dark surfaces convert more of the light to heat than light surfaces. Urban Microclimates: 1. What is a heat island? Common in large cities. Term used to describe the increased mean temperature cities have compared to the surrounding country side. 2. Describe how each of the following factors affect microclimates. a. Tall buildings Tall buildings facing one and other increase the surface area that is heated. b. greenhouse gases and aerosols air conditioners, cars, construction equipment that spew heat into the city. Fumes increase greenhouse gas. Aerosols – smokestacks, salty dust from snow clearing also add to heating. The solar radiation is absorbed by greenhouse gases and particles in the air and re-radiated into the local atmosphere c. ravines, waterways and wetlands In the country side more heat energy is used in evaporation therefore as a consequence less heat energy is available for heating in rural areas because so much is used in evapo-transpiration. 3. What is the advantage of full-grown trees? Cooling capabilities of five small air conditioners 4. What is canyon effect? Tall buildings affect wind currents (usually by blocking them). However, some winds roar between buildings with chilling speeds. (ex. Toronto financial district) 5. Why are large cities not often victim to tornadoes? Tall buildings block the winds and funnel dangerous storms outside of urban cities. 6. How to climatologists, engineers and planners want to improve the urban environment? Why? Plant gardens and grass on roofs of urban structures. Create a nice place to live, albedo of city would change – less heat would be produced because solar energy would be used for evapo-transpiration.