The instrument used for finding humidity levels in the atmosphere is the

The instrument used for finding humidity levels in the atmosphere is the

• A. Sling psychrometer
• B. Manometer
• C. Infrared thermometer
• D. Micron gauge

Answer: (A)

Measuring humidity hinges on how evaporative cooling varies with air moisture. A sling psychrometer uses two thermometers—one dry and one with a wetted wick. When you swing it, water evaporates from the wet bulb; the rate of evaporation depends on the surrounding humidity. In dry air, evaporation cools the wet bulb a lot, so the wet-bulb reading is noticeably lower than the dry-bulb reading. In humid air, evaporation is slower, and the two temperatures are closer together. The difference between these readings is then used to determine relative humidity via psychrometric charts or calculations. The other devices don’t measure humidity: a manometer gauges pressure differences, an infrared thermometer measures surface temperature, and a micron gauge measures very low pressures in vacuum systems. So the sling psychrometer is the instrument you use to find atmospheric humidity.

Measuring humidity hinges on how evaporative cooling varies with air moisture. A sling psychrometer uses two thermometers—one dry and one with a wetted wick. When you swing it, water evaporates from the wet bulb; the rate of evaporation depends on the surrounding humidity. In dry air, evaporation cools the wet bulb a lot, so the wet-bulb reading is noticeably lower than the dry-bulb reading. In humid air, evaporation is slower, and the two temperatures are closer together. The difference between these readings is then used to determine relative humidity via psychrometric charts or calculations.

The other devices don’t measure humidity: a manometer gauges pressure differences, an infrared thermometer measures surface temperature, and a micron gauge measures very low pressures in vacuum systems. So the sling psychrometer is the instrument you use to find atmospheric humidity.