Ice is considered 'on' if ice completely covers the body of water from your point of view.
- Choose a vantage point
- Can you see any exposed water?
- If no, ice is 'on'!
- Take a photo of your field of view for comparison and confirmation
From the same vantage point, report when you no longer see any ice.
What if ice melts after it's considered 'on'?
Researchers are looking for the longest continuous freeze. But they also like to know:
- The first date the ice completely covers the body of water
- The first date the ice completely disappears from the body of water
You can make note of these in comments for those days, but your official 'Ice on' and 'Ice off' should represent the longest continuous period.
Finding out trends
Every winter is different, so it can take a few years to find out if there's been any real changes. Make sure you keep track of the vantage point you're going to be observing from for each year.
Just because a lake is frozen all the way across does not mean it is safe for you to walk on. Take precautions to determine that ice is thick enough.