Microclimates are exactly that: phenomena measured on scales of inches to miles. The wind can be gusting to gale force near a ridgetop while only gentle breezes blow in the valley below. A simple garden wall may enable a plant to thrive where it otherwise would have been hard-pressed to survive. One house a block away from another may cost 50 percent less to heat. We may feel we have conquered climate with our heating and air-conditioning, but city planners as well as, say, orange growers, ignore such local effects at their peril.