Using a computer to predict the weather
Satellite image showing clouds
over the Great Lakes, USA (c) NASA
How computer models create weather
It's not enough to merely get weather data, however clever your
apparatus for collecting it - have a look at Where do weather
forecasts come from? for more information about collecting
weather data. To forecast the weather, you need to be able to use
the data to predict what's going to happen next in the
Weather forecasts are made by collecting quantitative -
numerical - data about the current state of the atmosphere. This
data is then put into a mathematical model, which will predict the
weather based on current conditions.
In mathematical models, raw data is entered into a computer. A
series of calculations is performed on the raw data on it to
determine how it will change over time. Normally, mathematical
modelling is done by computers, which can carry out many
calculations per second.
In the case of weather models, data such as rain fall,
temperature and wind speed are fed into a computer. The computer
performs calculations on - models - this data, using equations
produced from our scientific understanding of atmospheric
processes, such as fluid dynamics and thermodynamic equations.
These models allow forecasters to predict how the conditions in the
atmosphere will evolve. The more sophisticated and up-to-date your
model is, the more accurate your forecast should be. Powerful
supercomputers are needed to perform the complex calculations in
mathematical weather models.
Erin Roberts presenting S4C
weather using 1 kilometre radius forecast model
It's thanks to models that we can process raw weather data into
sophisticated and accurate forecasts. The model used to create the
unique 1 kilometre radius forecast on Weather Labs is the most
sophisticated model available. It is also used for the weather
forecasts on the Welsh television channel S4C.
Even the most sophisticated model can't be right all the time.
Have a look at Why
weather models can get it wrong to find out why.