Developments in the 17th and 18th centuries made weather forecasting more accurate. The 17th century saw the invention of the thermometer, which measures temperature, and the barometer, which measures air pressure. In the 18th century, Sir Isaac Newton was able to explain the complex physics of gravity, motion, and thermodynamics. These principles guided the science of meteorology into the modern age. Scientists were able to predict the impact of high-pressure systems and low-pressure systems, as well as such weather events as storm surges, floods, and tornadoes.