WATER IN THE AIR. Investigation 6- Water in the Air Enduring Understanding: Humidity is the water vapor in the air Learning Goals: I will use ice water.

WATER IN THE AIRWATER IN THE AIR

• Investigation 6- Water in the Air

• Enduring Understanding:

• Humidity is the water vapor in the air

• Learning Goals:

• I will use ice water to cool air to produce condensation.

• I will measure changes in temperature due to evaporation.

• I will determine dew point by cooling water in a container until condensation occurs on the container.

• I will observe changes in temperature due to pressure change.

• I will use pressure to produce a cloud in a bottle.

• I will explain how dew and clouds form when humid air cools to its due point and condenses.

• I will predict could formation by analyzing radiosound sound data.

• Now we know water Now we know water vapor is in the air. vapor is in the air.

• How does water vapor How does water vapor get into the air though?get into the air though?

QUESTIONQUESTION

• Dampen a small area on Dampen a small area on the back of both hands.the back of both hands.

• Gently blow on the wet Gently blow on the wet spot on your left hand to spot on your left hand to simulate wind.simulate wind.

CUP DEMONSTRATION CUP DEMONSTRATION (RESEARCH)(RESEARCH)

• What effect does wind have What effect does wind have on the wet spot?on the wet spot?

• Where did the water go that Where did the water go that was on your hands?was on your hands?

• Why did the wet spot feel Why did the wet spot feel cold?cold?

RESEARCHRESEARCH

PURPOSE What question are you investigating?

How can you measure temperature change

during evaporation?

RESEARCH Prior Knowledge

Look in a book, internet, ask someone

What do you know about evaporation already?

HYPOTHESIS What do you think is going

to happen?

I think the temperature will (increases, decreases, stays the same) during evaporation.

EXPERIMENT Design an experiment to test

your hypothesis? What are you going to do? Can someone else repeat

your experiment?

Materials: Thermometers, two pieces of muslin, two rubber bands, a paper towel, a cup of water. What is your plan, step-by-step? 1.______________________________________________________________ 2. ______________________________________________________________ 3. ______________________________________________________________ 4. ______________________________________________________________ 5.______________________________________________________________ 6.______________________________________________________________ 7.______________________________________________________________ 8.______________________________________________________________ 9.______________________________________________________________

Materials AvailableMaterials Available1.Cup of water

2.Two pieces of muslin

3.Two Thermometers

4.Two rubber bands

5.A paper towel (from the sink area)

ANALYSI S Watch and Observe Collect your data

Write down your observations, record your data:

CONCLUSION What did you learn?

What did you learn? Claim:

From this activity/experiment, I found out… Evidence:

I know this because…

• Water can change from a liquid to Water can change from a liquid to vapor only when energy is vapor only when energy is available.available.

• Evaporation requires energy.Evaporation requires energy.

• Energy in the form of heat in the Energy in the form of heat in the environment is usually the source environment is usually the source of energy to make evaporation of energy to make evaporation happenhappen

RESULTSRESULTS

WORD BANKWORD BANK

•CondensationCondensation= when water changes from a gas to a liquid.

WORD BANKWORD BANK

•EvaporationEvaporation= process where liquid water becomes a gas called water vapor.

HUMIDITYHUMIDITY

• Water vapor in the air is called humidity.

• When there is a lot of water vapor in the air, the air is humid. Humid air usually makes you feel sticky.

HUMIDITYHUMIDITY• The amount of water vapor in

the air changes as the temperature changes.

• The warmer the temperature, the more water vapor the air can hold. As air gets colder, it holds less water vapor.

HUMIDITYHUMIDITY• When air contains as much water vapor as it can, it is saturated. It takes a lot of water vapor to saturate warm air, but only a little bit of water vapor to saturate cold air.

RELATIVE HUMIDITYRELATIVE HUMIDITY

• Meteorologists often describe the amount of water vapor in the air in terms of relative humidity.

• Relative humidity is measured in percentages. Relative humidity compares the amount of water vapor in the air to the amount of water vapor needed to saturate the volume of air.

RELATIVE HUMIDITYRELATIVE HUMIDITY

• You might hear that the humidity today is 50%. That means that the air contains 50% of the amount of water vapor needed to saturate the air at today’s temperature.

• For example, 1kg of air at 25 degrees C can hold 20g of water vapor. If it’s holding 10g of water vapor, the relative humidity is 50%