CLASS: 4th – 6th 25 mins SESE (SCIENCE)
Curriculum Links - Temperature and Pressure
- Science - Learning about materials and how they behave. How temperature and pressure can change the states of matter.
- Weather - Children can connect this experiment to see how clouds and fog form
Learning Objectives - WALT (We are learning to…)
- Temperature and pressure
- States of matter
- Talk and Discussion - listening, questioning
- Collaborative/Cooperative Learning - group work
- Active Learning – Through observation and participation
- Skills through Content: observing, predicting, describing, recording,
What do we know about clouds? When warm air rises into the sky from earth, its pressure is reduced. This is why the higher away you go from earth the lower the air pressure. In the sky the warm air expands, cools down and begins to form clouds. Invisible particles in the air from pollution, smoke, dust etc. all help form clouds as the water droplets can attach themselves to the suspended dust molecules.
Since we know that clouds are formed from temperature and pressure differences, let's try and create our own! There are two methods of doing this experiment, one is easier and requires less equipment while the other will call for some assistance.
- Jam jar
- Ice and hot water
- Clear plastic bottle
- Foot pump
- Rubber stopper/cork
- Some alcohol
- Safety glasses
For this experiment we will look at how a cloud can form from temperature differences in a jam jar. Get some hot water and pour it into the jar, next turn the lid upside down on the rim and place some ice on it.
You will start to notice condensation on the glass. This is what happens when the steam from the hot water meets the cold surface of the glass, causing it to cool down and turn from a gas back into a liquid.
After leaving the jar to sit for 30 seconds, take the hairspray and gently spray some into the jar. You will notice that the water particles in the steam of the hot water latch onto the hairspray molecules and form a cloud in the jar!
We can create a cloud in a plastic bottle too! For this part you will need a pump, plastic bottleand some alcohol (hand sanitizer will work fine). You may need help finding these things so ask an adult to help with this experiment.
First, pour a little bit of the alcohol into the plastic bottle and swivel it around so it grips to the sides. Attach the pump to the top of the bottle (you can do this by sticking the pump pin through a cork and then putting it in as the bottle seal). Begin to pump the bottle with air.
Pumping the bottle forces the molecules to squeeze together or compress. This will increase the temperature and the pressure inside the bottle as we push in more and more particle. Once you can't get any more air into the bottle, stop pumping and get ready to quickly pull the seal from the bottle. When you do this a cloud will suddenly appear inside!
Releasing the pressure allows the air to expand, and in doing so, the temperature of the airbecomes cooler. This cooling process allows the molecules to stick together - or condense - more easily, forming tiny droplets. Clouds are nothing more than groups of tiny water droplets!The reason the rubbing alcohol forms a more visible cloud is because alcohol evaporates more quickly than water. Alcohol molecules have weaker bonds than water molecules, so they let go of each other more easily.
Since there are more evaporated alcohol molecules in the bottle, there are also more molecules able to condense. This is why you can see the alcohol cloud more clearly than the water cloud.
Other planets have clouds too! Venus has thick clouds made from sulfur-dioxide. This is very poisonous to humans.