At last! I have finished this extremely long and carefully edited PowerPoint and accompanying worksheet explaining the causes of aridity, well, 2 of them at least! I do plan to do another lesson on ocean currents and mountains for next week so please let me know if you would like those too.
When I first taught this topic I found it quite a complex topic, so I have tried to break it down in an easy to understand way and explain it step by step with the help of PP animations.
You can fill in the worksheet as you go through the PP, or do it afterwards to test your learning.
Since it took me such a long time to create this I thought I'd share it here in the hope that someone else gets some use out of it too. Please leave me a comment with feedback!