An aethrioscope (or æthrioscope) is a meteorological device invented by

Sir John Leslie Sir John Leslie, FRSE KH (10 April 1766 – 3 November 1832) was a Scottish mathematician and physicist best remembered for his research into heat. Leslie gave the first modern account of capillary action in 1802 and froze water using an air ...

in 1818 for measuring the chilling effect of a clear sky. The name is from the Greek word for clear – ''αίθριος''. It consists of a metallic cup standing upon a tall hollow pedestal, with a differential

thermometer A thermometer is a device that temperature measurement, measures temperature or a temperature gradient (the degree of hotness or coldness of an object). A thermometer has two important elements: (1) a temperature sensor (e.g. the bulb of a merc ...

placed so that one of its bulbs is in the focus of the paraboloid formed by the cavity of the cup. The interior of the cup is highly polished and is kept covered by a plate of metal, being opened when an observation is made. The second bulb is always screened from the sky and so is not affected by the radiative effect of the clear sky, the action of which is concentrated upon the first bulb. The contraction of the air in the second bulb by its sudden exposure to a clear sky causes the liquid in the stem to rise. The device will respond in a contrary fashion when exposed to heat radiation and so may be used as a

pyrometer A pyrometer is a type of remote-sensing thermometer used to measure the temperature of distant objects. Various forms of pyrometers have historically existed. In the modern usage, it is a device that from a distance determines the temperature of ...

too.

References

Thermometers 1818 in Scotland 1818 in science Atmospheric physics Atmospheric radiation {{climate-stub