History of The Weather Channel originally generated only text-based products. Radar imagery was added to the units in June of that year, with graphical backgrounds being introduced in July, making the 4000 the first STAR to be capable of generating graphics and the first to incorporate the channel's logo in the forecast segments. Also in 1990, The Weather Channel began including snow condition reports at five minutes after the hour. Largely considered the height of the classic TWC by enthusiasts, The Weather Channel underwent a major graphical revamp (with the introduction of a new slogan, "Weather You Can Always Turn To") on March 6, 1991.
Irrational number During the 14th to 16th centuries, Madhava of Sangamagrama and the Kerala school of astronomy and mathematics discovered the infinite series for several irrational numbers such as "π" and certain irrational values of trigonometric functions. Jyeṣṭhadeva provided proofs for these infinite series in the "Yuktibhāṣā". In the Middle ages, the development of algebra by Muslim mathematicians allowed irrational numbers to be treated as "algebraic objects". Middle Eastern mathematicians also merged the concepts of "number" and "magnitude" into a more general idea of real numbers, criticized Euclid's idea of ratios, developed the theory of composite ratios, and extended the concept of