Which instrument is used to measure both wet bulb and dry bulb temperatures?

The correct choice is the instrument used to measure both wet bulb and dry bulb temperatures, which is the psychrometer. This device typically consists of two thermometers: one measures the ambient air temperature (the dry bulb), while the other has a wet wick that provides the wet bulb temperature reading by measuring the cooling effect of evaporation.

The psychrometer is especially useful in determining relative humidity, which is critical for applications in HVAC and meteorology. The data obtained from a psychrometer can be used in calculations involving air properties, making it essential for HVAC professionals and others working with climate control systems.

In contrast, a thermometer measures temperature but does not provide moisture readings. A pyranometer specifically measures solar radiation, and therefore does not pertain to temperature measurements related to humidity. The term "pyschrometer" appears to be a typographical error or misspelling and is not a recognized instrument in this context. Hence, the psychrometer is the appropriate choice when measuring both wet bulb and dry bulb temperatures.