Climate, Microclimate, and Climate Change

Weather is the combo of

  • temp

  • humidity

  • precipitation

  • wind

  • cloudiness

  • specific place and time

Climate

  • long-term average

Solar radiation and its design implication

Surface temperature

  • reflects the difference between income and outgoing radiation

  • Hot surfaces like the Sun - gives off shortwave (solar) radiation

    • the hotter the surface, the shorter the radiation wave is

  • Cooler objects like Earth’s surface - emit long wave (terrestrial) radiation

Albedo - is a function of surface reflectivity

  • expressed as a proportion (0-1)

  • more reflectance = cooler surface/less heat absorbed

  • less reflectance = hotter surface/more heat absorbed

HIGH ALBEDO IS BETTER FOR COOLING

Cities get hotter than surrounding rural areas because

  • low-albedo surfaces trapping heat (asphalt)

  • lack of vegetation (higher albedo > dark manmade surface)


Microclimate

  1. (Air) Temperature

On the perimeter of the city, the urban heat island decline sharply where the urban landscape quickly changes to the rural.

  1. Wind inside a city

  • highest velocities are reached on the windward brow and across the roof of the tallest building

    • Strong flow of air - deflected down the building face

    • Calm zone develops in the space between the buildings

    • Accelerated flow is associated with the canyon between large buildings

  1. Air Quality profile

  • pollution levels vary sharply from one sector of urban to another

  • Large particulates tend to be concentrated close to their sources

Summary

  • air temperature and relative humidity are hard to be modified through LS design

  • wind and radiation are easier to be modified through LS design

Deciduous woody plants

  • provides shade in summer and allows solar radiation through in winter

  • has minimal effect on wind, but we don’t want the cold wind during winter when the leaves fall off

Coniferous woody plants

  • year-round shade, benefit in summer but detriment in winter

  • substantial effect on the wind

best way to design a house with trees

  • summer sun doesn’t hit the roof

  • winter trees protect the house

Introduction to Climate Change

  1. in the past earth has been very warm

  2. the climate increases today, quicker than ever

direct impact (temperature)

  • heatwaves, wildfires, ice sheet melting, sea level rise

  • precipitation will also increase

    • because the water holding capacity of air will increase

Indirect impact

  • extreme precipitation, tropical cyclones, flood, drought