Microclimates

A microclimate refers to a specific small area that has a climate different from the larger area around it. Eco-landscapers who work in regions that have many diverse microclimates must understand these differences in

Xeriscaping incorporates the best techniques for reducing water waste; xeriscapes often occur in very hot, dry climates. Irrigation covers any area that needs extra water, but it does not waste water on drought-resistant plants. Porous materials for driveways, walkways, and patios allow rainwater to run into the ground, as does the replacement of lawn with gravel.

order to select the best plants for a particular parcel of land. Some microclimates spread over several acres, but other microclimates are so distinct, they cover no more than a half-acre.

 The U.S. Department of Agriculture (USDA) publishes a “Plant Hardiness Zone Map” that shows North America divided into 21 distinct climate zones and helps landscapers and gardeners understand their unique growing conditions. Each different zone on the map contains conditions suitable for certain plants, and landscapers are wise to select plants that do best in these zones. But even within such discrete climate zones, much smaller microclimates often exist. The San Francisco Bay Area in California is a champion of sorts in microclimates: It contains 20 major microclimates and perhaps hundreds of small microclimates across its nine counties. In less than an hour, a person can drive from a hot, dry 100°F (38°C) climate to foggy and windy 50°F (10°C) conditions. During that journey, the driver will likely pass through rain, sunshine, and varying degrees of heat and cold. The San Francisco Chronicle writer Harold Gilliam explained in 2001, “The reasons for this extraordinary variety of weather lie deep in the geologic past—in the clash of tectonic plates. The Pacific plate of the Earth’s crust, moving eastward over the eons, smashed into the edge of the North American continental plate, prying it up into monumental chains of mountains, including the Sierra Nevada, and, much later, California’s coast ranges. It is this rumpled landscape, this hill-and-valley topography, this heterogeneous diversity of landforms that give the Bay Area its multiple climates, microclimates, and submicroclimates.” Each eco-landscape therefore consists of a design best suited to its microclimate.

Environmental engineers must understand geography and climate when seeking energy efficiency because these things contribute to microclimates, which in turn influence the efficiency of buildings and landscaping. The following list summarizes the factors that engineers consider when working with a microclimate:

1. path and intensity of sunlight
2. wind and rain directions
3. wind forces
4. barometric pressure patterns
5. morning, midday, and evening temperature and humidity
6. coldest and warmest temperatures by season
7. cold air drainage
8. soil evaporation rates and tree transpiration rates
9. bodies of water that absorb daily heat and moderate temperatures
10. north- or south-facing slopes
11. soil composition, chemistry, and moisture

 Microclimates and all the many factors they encompass explain why environmental engineers require training in diverse sciences in order to work within the natural boundaries of nature.