Can Turgrass Change The Air Temperature?

Temperature Modification

Have you ever had the pleasant experience of walking barefoot in the yard and feeling how cool the grass is?  Of course, many of our reel mower enthusiasts ecomow in their bare feet.  Grass obviously plays an important role in controlling our outdoor climate.

Studies  show that grass can cool the air temperature by absorbing the sun’s heat during the day and releasing it slowly in the evening, thus moderating temperature. The grass will absorb some of the solar radiation to fuel the photosynthesis process. Grass areas also have irregular surface area which scatters light and radiation, greatly reducing glare.

Turf grass will cools itself and its surroundings by a process know as evapo-transpiration.  Transpiration from the grass blade, and evaporation from the soil. An acre of turf on a summer day will lose roughly 2,400 gallons of water through evapotranspiration to the atmosphere. Roughly 50% of the sun’s heat striking the turf may be eliminated through this transpirational cooling process.

The cooling properties of turf are so effective that temperatures over turfed surfaces on a sunny summer day will be 10 – 14 degrees cooler than over concrete or asphalt. Or to put it another way, consider the fact that on a block of eight average homes, the front lawns have the cooling effect of 70 tons of air conditioning!

Research studies revealed overall temperature of urban areas may be as much as 5 to 7 °C warmer than that of nearby rural areas. Through the cooling process of transpiration, turfgrasses dissipate high levels of radiant heat in urban areas. Maximum daily canopy temperatures of a green, growing Cynodon turf (Bermuda grass) was found to be 21 °C cooler than a brown dormant turf and 39 °C cooler than a synthetic surface (Table 1; Beard and Johns, 1985). The transpirational cooling effect of green turfs and landscapes can save energy by reductions in the energy input required for interior mechanical cooling of adjacent homes and buildings (Johns and Beard, 1985).

Source:
“Environment Temperature Modification,” The Lawn Institute http://www.thelawninstitute.org/environment/?c=185540 [accessed on June 30, 2009].