Clouds are an all too familiar sight in our climate. Clouds form on Earth when water on the ground, in stores of the water cycle, is heated by the sun. Vapour forms which acts as warm air, this air rises and pressure is reduced, when the air expands it cools and hence the temperature drops below the dew point – when cold air cannot hold as much water vapour as warmer air, it has less carrying capacity. Many particles are present within the air, including pollution, smoke and dust, such materials act as a nucleus to which water molecules can attach. When such molecules collide together again and again, a cloud forms.
Can the presence of clouds be linked to changes in our climatic conditions? Since just 1950, the planets average surface temperature has risen by around 1.62 degrees Fahrenheit. Clouds reflect sunlight, which cools the earth as there are less direct rays hitting our surface. However, they also have the opposing effect in trapping heat, in a familiar fashion to greenhouse gases, which warms the Earth. Overall, the net impact that clouds have on climate change can be seen as seemingly neutral.
You will need:
- An empty soft drink bottle with a cap, 1.5 litre.
- Warm water.
- A lightened match.
- Firstly, take warm water and fill the empty 1.5 litre bottle around two thirds full. Place the cap back onto the bottle.
- This will make water vapour.
- Following this, remove the lid and drop a lightened match into the bottle, quickly putting the cap back on.
- This will produce smoke – acting as particles.
- Finally, squeeze the bottle hard and release, this increases the air pressure.
- Observe the artificial cloud as the air pressure drops.
You can print off a word search to help young scientists learn some new vocabulary from this experiment.
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In the research lab
Y4 Pupils should be taught to:
- compare and group materials together, according to whether they are solids, liquids or gases
- observe that some materials change state when they are heated or cooled, and measure or research the temperature at which this happens in degrees Celsius (°C)
- identify the part played by evaporation and condensation in the water cycle and associate the rate of evaporation with temperature
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