Longjing tea of a finer Longjing is achieved only by using a genuine, slightly porous, Yixing clay teapot, which since the beginning, was popular exactly for preparing green tea well. The tea can be very expensive, and the prices depend on the varieties, of which there are many. Longjing is divided into six grades: "Superior" and then 1 down to 5. Infused leaves are a good indicator of quality, which is characterized by maturity and uniformity of the shoots harvested for processing. High quality Longjing teas produce tender, whole leaves that are uniform in appearance. Lower quality varieties may vary in color
Tianchi basin Tianchi basin As precipitation was for important agriculture and food production, the Song Chinese mathematician and inventor Qin Jiushao developed a precipitation gauge that was widely used in 1247 during the Southern Song dynasty to gather meteorological data. Qin Jiushao later records application of rainfall measurements in the mathematical treatise "Mathematical Treatise in Nine Sections". The book also discusses problems using large snow gauges made from bamboo situated in mountain passes and uplands which are speculated to be first referenced to snow measurement. Tianchi basins were installed at provincial and district capitals and bamboo snow gauges were situated in mountain