answersLogoWhite

0

A hygrometer is used to measure relative humidity. The two thermometers in a hygrometer are different in that one is a "regular" thermometer and the other has some batting (a wrap) around the bulb that is kept wet. The thermometers are called a dry-bulb thermometer and a wet-bulb thermometer, respectively. The dry-bulb thermometer measures "regular" or ambient air temperature. The wet-bulb thermometer will measure a cooler temperature (usually) because moisture evaporating from the wrap around its bulb will cool it down below ambient temperature. Below zero, the wrap freezes and the wet-bulb thermometer will read a higher temperature (usually) than its dry-bulb companion. The dry-bulb thermometer will tell us the actual ambient temperature of the air. It's a very necessary baseline. There is a maximum amount of moisture that air at a given temperature will hold. (Higher air temperatures will allow air to hold more moisture and lower air temperatures will not allow as much.) What we need to know is what fraction (the percentage) of moisture the air is holding relative to the maximun it can hold. That's why we call it relative humidity. It is the wet-bulb reading that is critical now. The hygrometer looks at the difference between the dry- and wet-bulb temperatures. This number, the difference, is looked up on a psychrometric chart, and for a given ambient temperature and a given temperature difference, there is only one relative humidity that will be possible. The psychrometric chart is a calibrated "graph" that has been drawn up from precise laboratory measurements of the way the two thermometers will react for a given ambient temperature and a given temperature difference (which means a specific relative humidity). A link is provided to the Wikipedia article on the hygrometer so you can see some pics and do some additional reading.

User Avatar

Wiki User

17y ago

What else can I help you with?

Continue Learning about Physics

Two kinds of thermometer?

Two common types of thermometers are digital thermometers and mercury thermometers. Digital thermometers use electronic sensors to measure temperature and display it on a screen, while mercury thermometers contain mercury that expands or contracts with temperature changes. Mercury thermometers are being phased out due to environmental concerns over mercury exposure.


How do you find the temperature gradient between two thermometers?

To find the temperature gradient between two thermometers, subtract the temperature reading of the first thermometer from the temperature reading of the second thermometer. This difference represents the temperature change over the distance between the two thermometers, indicating the temperature gradient.


What is least count in hygrometer?

The least count of a hygrometer typically refers to the smallest change in humidity that can be measured by the device. This value is determined by the precision and resolution of the hygrometer's sensors and display, and can vary depending on the specific model and design of the hygrometer.


What has two thermometers (a wet bulb thermometer and a dry thermometer)?

A psychrometer has two thermometers: a wet bulb thermometer and a dry bulb thermometer. It is used to measure relative humidity and can also determine dew point.


What are 3 main different types of thermometers?

The three main types of thermometers are liquid-in-glass thermometers, digital thermometers, and infrared thermometers. Liquid-in-glass thermometers use a liquid like mercury or alcohol to measure temperature, digital thermometers provide a numeric temperature reading, and infrared thermometers measure temperature from a distance using infrared technology.

Related Questions

What instrument measures relative humidity using two thermometers?

hygrometer psychrometer


Which instrument measures relative humidity without thermometers?

A hair hygrometer.


What instrument measures relative humidity using wet-bulb and dry-bulb thermometers?

Hygrometer


What rhymes with kilometer?

Hydrometer, hygrometer, micrometer, millimeter, odometer, spectrometer, speedometer, thermometer


How a hygrometer work?

Any instrument for measuring the humidity, or water vapour content, of a gas (usually air). A wet and dry bulb hygrometer consists of two vertical thermometers, with one of the bulbs covered in absorbent cloth dipped into water. As the water evaporates, the bulb cools, producing a temperature difference between the two thermometers. The amount of evaporation, and hence cooling of the wet bulb, depends on the relative humidity of the air.


How does a hygrometer?

Any instrument for measuring the humidity, or water vapour content, of a gas (usually air). A wet and dry bulb hygrometer consists of two vertical thermometers, with one of the bulbs covered in absorbent cloth dipped into water. As the water evaporates, the bulb cools, producing a temperature difference between the two thermometers. The amount of evaporation, and hence cooling of the wet bulb, depends on the relative humidity of the air.


How does a hygrometer units measure?

A hygrometer measure humidity. One sort of hygrometer is psychrometer, it has two thermometers one kept wet the other dry. The difference between the temperatures is related to the humidity.


What is used to mesure humidity?

Humidity is typically measured using a hygrometer, which can be either a mechanical or electronic device. The most common type of hygrometer is a psychrometer, which uses wet and dry bulb thermometers to determine the relative humidity in the air.


What is a psycrometer?

This is an instrument used to measure the relative humidity in the air.[Another way of determining this is to measure the dew point of the air. The temperature at which dew will form on a clean mirror that can be chilled. ]


What is the difference anemometer and hygrometer?

An anemometer measures wind speed. A hygrometer measures relative humidity. Two different things entirely.


What is the difference between anemometer and hygrometer?

An anemometer measures wind speed. A hygrometer measures relative humidity. Two different things entirely.


How does a hygrometer work?

Any instrument for measuring the humidity, or water vapour content, of a gas (usually air). A wet and dry bulb hygrometer consists of two vertical thermometers, with one of the bulbs covered in absorbent cloth dipped into water. As the water evaporates, the bulb cools, producing a temperature difference between the two thermometers. The amount of evaporation, and hence cooling of the wet bulb, depends on the relative humidity of the air.