Ground-truth, the eyewitness verification of atmospheric conditions, is an important part of weather reporting. It supplements the data received from remote-sensing equipment like radar and satellites.
On a recent trip to Bermuda, an island that gets its fair share of severe weather, I came across the Early Bermuda Weather Stone in a park near Fort Scaur. At first glance I thought this was a bit of local humor, but then it hit me. This hanging rock is exactly what it claims to be, “…the perfect weather indication.” In essence, it is a ground-truth indicator. The instructions on its sign sum up how to verify the current local atmospheric conditions. It states:
- A dry stone means… it is not raining.
- A wet stone means… it is raining.
- A shadow under the stone means… the sun is shining.
- If the stone is swinging it means… there is a strong wind blowing.
- If the stone jumps up and down it means… there is an earthquake.
- If ever it is white on top… believe it or not… it is snowing.