Weather Weather InstumentsInstuments

ThermometerThermometer

Thermometers Thermometers measure air measure air temperatures. temperatures. Thermometers Thermometers work because work because matter expands matter expands when heated. when heated. Most Most thermometers are thermometers are closed glass tubes closed glass tubes containing liquids containing liquids such as alcohol.such as alcohol.

BarometerBarometer

A barometer A barometer measures air measures air pressure.pressure.

There are There are two types of two types of Barometers: Barometers: Mercury Mercury Barometer Barometer and Aneroid and Aneroid Barometer.Barometer.

Aneroid Barometer Mercury Barometer

A Mercury A Mercury Barometer Barometer consists of a glass consists of a glass tube inserted into tube inserted into a dish of mercury a dish of mercury or colored or colored denatured alcohol.denatured alcohol.

The surrounding air The surrounding air presses down on presses down on the mercury in the the mercury in the dish and forces dish and forces some of the some of the mercury up into the mercury up into the tube. The height to tube. The height to which the mercury which the mercury rises in the tube is rises in the tube is directly directly proportional to the proportional to the atmospheric atmospheric pressure.pressure.

HygrometerHygrometer

A hygrometerA hygrometer measures the measures the

humidity of the humidity of the air. One of the air. One of the two two thermometers thermometers has a wick has a wick (cloth cover) (cloth cover) which is dipped which is dipped in distilled in distilled water.water.

Evaporation of Evaporation of water from the water from the wick on the wet wick on the wet bulb thermometer bulb thermometer leads to cooling. leads to cooling.

Using a Using a Relative Relative Humidity TableHumidity Table, , the temperature the temperature difference between difference between the two the two thermometers thermometers gives the relative gives the relative humidity of the air humidity of the air (in percent).(in percent).

This is an This is an example example of the of the type of type of table you table you would would use. Your use. Your book book might might also also have an have an example.example.

Anemometer

An Anemometer An Anemometer measures the measures the wind speed. The wind speed. The cups catch the cups catch the winds, turning a winds, turning a dial attached to dial attached to the instrument.the instrument.

Think you could Think you could build one of build one of these?these?

WIND VANE

Shows the wind direction

Rain Gauge

Time for a little Time for a little review!review!

1.1. If I wanted to If I wanted to find out if the find out if the pressure was pressure was rising, I’d use rising, I’d use which of the which of the following?following?

2.2. Used to Used to determine the determine the relative relative humidity.humidity.

A)A) ThermometerThermometerB)B) BarometerBarometerC)C) PsychrometerPsychrometerD)D) Wind VaneWind VaneE)E) Rain GaugeRain GaugeF)F) AnemometerAnemometer

3. Can help you 3. Can help you find out the find out the wind speed.wind speed.

4. If I wanted to 4. If I wanted to know the know the difference difference between the between the temperature temperature inside and inside and outside of the outside of the classroom.classroom.

A)A) ThermometerThermometerB)B) BarometerBarometerC)C) PsychrometerPsychrometerD)D) Wind VaneWind VaneE)E) Rain GaugeRain GaugeF)F) AnemometerAnemometer

How did you do? Here How did you do? Here are the correct are the correct

answersanswers1.Barometer1.Barometer2. Psychrometer2. Psychrometer3. Anemometer3. Anemometer4. Thermometer4. Thermometer