I did something different. I made tea with cold water. The results?
I learned that tea does not need hot water. However, different varieties of tea need to be steeped for different amount of times at different water temperatures in order to get optimal flavor. Steeping for too long at too high or low a temperature will make the tea bitter.
But basically compounds in the tea leaves get released and mixed in with the water. Hotter water makes this happen faster.
Hot water has more energy at the molecular level than cold. This causes its molecules to more efficiently penetrate and soak into stuff it touches, and as a result it's better at dissolving things and pulls the molecules responsible for flavors and colors out of those dried tea leaves faster. So immersing your teabag or leaves in hot water extracts the flavor more completely and more quickly.
Further, warm temperature liquids taste different, often stronger, and smell different and stronger too. As tea a usually a mild drink, a warm tea will have a stronger flavor and a stronger scent than a cold one.
Tea can be brewed in cold water, it just takes a lot longer and results in a cold beverage with a different taste.
It's very similar to food. Certain foods need to be eaten hot because the aroma is half the taste.