With snow, it is cold outside. This is a yin condition. Teas are graded by various factors which include degree of yin or yang, coldness or hotness. Therefore, to counter yin(cold, dark, wet), oftentimes a yang tea is needed. Black teas are yang. Yes teas all use hot water, but some are more yin, like green and white teas, and some more yang, such as black teas. Heating teas are especially valuable in locales such as Calgary Alberta which regularly experience -30 in the winter. In temperatures like this it is unfortunate that machinery cannot be made to work better with something as simple and fun as a cup of black tea.
That makes so much sense! It also explains why everyone has been recommending black teas and chais!!!
There is actual research(google scholar) that says that T lymphocyte activity was definitively increased with black tea, the other teas dont have the same composition and hence not the same effect.