Accurate weather forecasting, even with supercomputers, relies on getting a detailed picture of the atmosphere at any moment in time and then predicting what the air will do next. Measurements are taken using weather balloons, remote weather stations, ships and buoys. By the time data are collected into a model things have unfortunately already changed. Forecasters typically get tomorrow's weather right 85% of the time - but when asked what's going to happen in five days' or a week's time their accuracy falls to 55%. Dedicated weather satellites are already in orbit, scrutinising our atmosphere, but the resolution of their sensors is quite coarse - tens or even hundreds of kilometres. This week a new weather and climate satellite called Aqua launches from Cape Canaveral in Florida, USA to kick off a new age of weather monitoring. Placed into what's called a polar orbit 700km up - it will stay in the same point in space relative to the Sun, and look down on the whole Earth turning beneath every day. Its battery of sensors will measure infrared and microwave radiation as it leaves the Earth's atmosphere - translating this into detailed vertical temperature and moisture profiles through the air, and tracking the global water cycle accurately. Meteorologists (the weather experts) hope that Aqua and other next generation weather satellites like the new Eumetsat, due for launch in August, will make long range weather forecasts more accurate and improve predictions of how and why our climate seems set to change.