Frost is an interesting process that occurs on clear cold nights when turfgrass plants reradiate heat (exothermic reaction). As the plant loses heat to the atmosphere the plant leaf cools. If the plant temperature is cooler than the air temperature then moisture from the atmosphere will condense on the leaf.
Should the leaf temperature drop below freezing then the water freezes and frost forms. This will occur even if the air temperatures are slightly above freezing. At this time of the year it is not uncommon to have frost form even if the air temperature is in the mid to high 30's.
Frost does not form as readily on cloudy nights because the clouds reflect, or absorb and then reradiate the energy back towards the turf. Thus, the plants receive heat from this rerediation. Frost also does not form as readily under conditions where a breeze is present.
Through convection the mixing air closest to the plant and the atmosphere buffers the leaf temperature drop (also promotes evaporation of the water droplets from the leaf). Areas with little slope have a greater potential for frost than sloping areas (air moves downward resulting in a mixing).
Frost will normally form early in the morning before sunrise. This makes sense because if the plants have been reradiating energy throughout the night, the leaf temperature should be the coolest prior to daybreak. Actually frost may continue to form briefly even at daybreak due to the low angles of light coming from the sun may not directly hit the leaf.When frost is present golf course superintendents delay play until the frost has melted. This is done to prevent damage that affects the quality of the playing surface and could potentially be very expensive to repair.
Frost is basically frozen dew that has crystallized on the grass, making it hard and brittle. A grass blade is actually 90 percent water, therefore it also freezes. Because of the short mowing height (4mm in the Winter) and fragile nature of the turf, putting greens are most affected by frost. Walking on frost-covered greens causes the plant to break and cell walls to rupture, thereby losing its ability to function normally. When the membrane is broken, much like an egg, it cannot be put back together.
Golfers who ignore frost delays will not see immediate damage. The proof generally comes 48-72 hours later as the plant leaves turn brown and die. The result is a thinning of the putting surface and a weakening of the plant. The greens in turn become more susceptible to disease and weeds. While it may not appear to be much of an issue if a foursome begins play early on frost covered greens, consider the number of footprints that may occur on any given hole by one person is approximately 60. Multiply that by 15 holes with an average of 110 rounds per day and the result is 99,000 footprints on greens in a day.
Key points to be aware of:
Frost is basically frozen dew that has crystallized on the grass, making it hard and brittle. A grass blade is actually 90 percent water, therefore it also freezes.
Walking on frost-covered greens causes the plant to break and cell walls to rupture, thereby losing its ability to function normally.
When damaged, the putting surface weakens and becomes more susceptible to disease and weeds.
One foursome can leave several hundred footprints on each green, causing extensive damage.
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