The Damage by Frost

[knocker]

In recent months I've been doing a fair bit of research that involves scouring US newspapers, Inevitable one gets sidetracked as other items catch the eye and this was the case here. It's some early thoughts on ground temps, radiation and plant protection. Not without interest I thought.

Pacific Rural Press, Volume 12, Number 13, 23 September 1876

The Damage by Frost.

We have formerly urged the advantage of protection against frost and recorded practical success with the employment of smoke clouds. We read that in some of our mountain counties and in Nevada the frost has already nipped garden crops. In this connection we print the following important facts in reference to the surface temperature of the earth, and the effect of shelter, which- Dr. Barham communicates to the Royal institute of Cornwall, England. He says that the very considerable difference between the lowest temperature, as indicated by the self-registering thermometer placed within a thermometer screen, and that shown by a similar instrument exposed on the grass and radiating freely into space, is an illustration of the influence of shelter.

The common estimate of the greatest cold of night is derived from the record of the thermometer screened from radiation. This is what passes current as the minimum temperature, and that not only among the public, but also generally with those who pay a good deal of attention to meteorology. Yet when the sky is dear, the temperature of the grass, and that to which vegetables, men, and animals out of doors are exposed, will be from five to ten degrees lower, and sometimes more; and it is just these additional degrees of cold that when an ordinarily sheltered thermometer indicates a pretty sharp frost, destroy tender plants and often more or less seriously affect the health of the delicate, the old, and the very young.

According to the records of Captain Liddell the radiating thermometer was, during 1872 and 1873, on 25 occasions, from 10 degrees to 13 degrees colder than the sheltered thermometer. Most of these cases occurred daring April, July, and August. It is found that garden loam has the power of receiving and retaining heat superior to that of any other naked soil. The temperature of peat is nearly equal to that of garden loam although it is wet and cold to the sense of touch. A covering defends the naked soil from these extreme effects of radiation, no matter whether the covering be a natural one of grass, or an artificial one, such as screens of muslin, straw matting, clouds of smoke, or mist. The beneficial effect of a covering of muslin is not quite equal to that of straw matting, but the amount of protective influence of so slight a material is worthy of notice, amounting on the average to nearly one and one-half degrees, and in some cases to three degrees. It is said, as a general result, that in the climate of Cornwall the soil covered with vegetation will be from eight to ten degrees warmer in sharp frosts if screened from the sky by straw matting or other moderately thick materials spread over three or four feet from the ground.

Edited March 31, 2017 by knocker