Experiments with Sunshine

Now we know more about sunshine, let's do some experiments together to demonstrate some of these ideas.

Firstly, find a blackboard that is partly in the sun and partly in the shade. Wipe a wet cloth across it. What happens to the water? Which part of the blackboard does it evaporate most quickly from?

Try a similar thing with ice cubes. If you put some ice cubes in the sun and another lot in the shade, which ones will melt first?

Hot and Cold

We can see from these experiments just how powerful the sun can be. But what is the sun actually doing that is causing the water to evaporate and the ice to melt? I’ll give you a clue. It is changing something that we measure with a thermometer. That’s right – temperature! The sun’s rays cause the temperature to increase, meaning water will evaporate and ice will melt more quickly.

Temperature is a measure of how hot or cold the air is. It is very important in helping us understand changes in the weather. Although our bodies sense when the temperature rises or falls, they cannot do this very accurately and so we use a thermometer to measure it for us instead.

Thermometers measure temperature using mercury which expands when it warms up. The measurements are made in degrees centigrade (°C) or degrees Fahrenheit (°F).

To convert °F to °C, subtract 32, multiply by 5 and divide by 9.

To convert °C to °F, multiply by 9, divide by 5 and add 32.

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Or:  Use this automatic temperature converter below!

As well as the amount of sunlight received, there are also a number of other factors which can affect the temperature of an area or object.

As we have already seen, if something is placed in direct sunlight its temperature will be higher then if it was in the shade. You can test this yourself by placing a thermometer in different locations and comparing the results. How are the readings different if the thermometer is:

• in sunlight?
• in the shade?
• on the ground?
• in the air?

Air temperature is also affected by the time of year and time of day. To see how seasons and days alter the temperature in your area, take a selection of different recordings using your thermometer. Make a chart for each day using squared or graph paper, and note down the temperatures at different times of day for one week each month. Can you guess what the temperature will be before you look at the thermometer?

Use the figures you have collected to see what the highest and lowest temperatures you recorded were. When did they occur – at what time of day and year? This will help you see how temperature can change during the day and also over a year. 

We will learn more about such temperature variations on the next page.