Experimental Studies on the Effect of a Parasol for Avoiding Summer Heat

Abstract

  In summer we use parasols, hats or caps to avoid heat waves from the sun.

  The results of the mimic experiment on the heat preventive effect of parasol raw materials were already reported previously, and in the present study a human experiment was performed under the sun's rays and under the infrared electric bulb, using the same sample.

  The sites of determination were the crown of the head, forehead, nuchal region, shoulder, upper abdominal region, trunk, axillary region, ventral femoral region, and anterior crural region for skin temperature, together with the temperature in the hair, and the surface tempetature of the clothes over the shoulder.

  The rise in temperature in 20 minutes after irradiation was determined with a thermister thermometer and a thermograph.

  The following results were obtained after the experiment :

1. The same conclusion was obtained after the mimic experiment and the human experiment.

  The good order of the heat insulation property of parasols are silber foil, double layers, white thick cloth, black curtain-cloth, black linen cloth, white linen cloth, black thin cotton cloth, white thin cotton cloth.

2. The rise in temperature particularly in the hairs at the crown of the head was remarkable among all sites of determination.

3. By using samples B_L and W_L made of the same material, but the colours were different, the influence of secondary radiation was examined : when the rise in temperature was at the distance of 5cm, black was highest, while when it was at the distance of 15cm, white was highest, but reversal was observed at 10cm.

4. It was observed for the conditions of the heat prevention of the parasol that the porocity of the cloth mattered more than the colours. It is therefore more desirable to use a thick cloth not permeating light, made of a yarn with high density and high covering capacity.