Everything we build in our landscape effects microclimate, the highly local variant of a region’s general climate. Landform, vegetation, water, and surface treatments are among the factors that influence our comfort level – as well as thermal pollution. The photo above shows an “oil and stone” driveway with a pebble swale alongside. It was paved with light-colored granite chips, and therefore has a much higher albedo than an asphalt driveway. Albedo is the measure of a surface’s tendency to reflect radiation. Dense, dark materials like asphalt have albedos near zero, while fresh snow is almost impermeable to radiation, with an albedo near 1.0. That is the range. Most of us are familiar with the “heat island” effect of asphalt parking lots. That refers to the way their surfaces absorb radiation and release it after the sun goes down. Albedo is an important consideration in the design and selection of pavement and rooftop materials, especially in densely developed communities.