Seasons: part 2
Practical Activity for 14-16
In this demonstration, a lamp, world globe and a strip of self-adhesive thermochromic plastic are used to show how the the surface temperate of the Earth varies according to the angle of the sunlight reaching it.
Apparatus and Materials
- World globe
- Self adhesive thermochromic plastic
Health & Safety and Technical Notes
- The self-adhesive thermochromic plastic is cut into a strip and placed vertically on the globe next to the country that is of interest to you.
- The lamp will need to be placed at a distance that warms the globe enough to cause a change in temperature that makes the plastic change colour. If the lamp is too near the plastic will get too hot, change colour and then go black again. If it is too far away it will not change colour at all.
- The demonstration shows that when sunlight hits the surface of the Earth at different angles, the energy transferred to the Earth by light and heat is spread out over different areas. Where the angle would place the Sun low down on the horizon, the energy is spread over a larger area and the Earth does not heat up as much
- Thermochromic paper can show a range of colours from brown through to blue. You will need to explain to students that brown is cooler and blue is hotter.
- As with Seasons - Part 1 , you could extend this idea and use a light sensor to show the difference in light intensity.
- You could try placing a web camera at different places on the Earth and point it at the lamp (i.e. the Sun) so that you can see how low or high the Sun is at that time of year.
- This demonstration leads directly from Seasons - Part 1