Levels of boiling

As you brew tea, you notice that different types demand different temperatures. I don’t use a fancy kettle, simply a pot filled with water. I also don’t have a thermometer, but I was sure there had to be a way to tell the temperature using my eyes. Wikipedia came to the rescue:

shrimp eyes: about 70-80 °C (155–175 °F) – separate bubbles, rising to top
crab eyes: about 80 °C (175 °F) – streams of bubbles
fish eyes: about 80-90 °C (175–195 °F) – larger bubbles
rope of pearls: about 90-95 °C (195–205 °F) – steady streams of large bubbles
raging torrent: rolling boil, swirling and roiling