Going back as early as 350 before Christ Aristotle wrote about weather patterns. Even though it's far from today's weather forecasting, it was the start of something that still fascinate us: The ability to understand and predict the weather.

To make a forecast metereologists collect data from several sources which are then fed into mathematical models. But in spite of all the advanced technology of our modern society, forecasting will always be an educated guess. How can this be?

This is because the weather is a so called chaotic system. That means that even a small error in the early forecast can grow into huge variations in the real future weather. For that reason, there will always be a limitation to the accuracy of weather predictions.

But in fact, weather forecasts are basically pretty accurate. Today, a five day-forecast has usually an accuracy of around 90%. For a seven day-forecast the numbers go down to approximately 80%. As the number of days increases, so does uncertainty. And after 15 days, it is virtually impossible for the forecasters to say anything qualified.

These numbers are also much better than what they used to be. Due to technological developments, a seven day forecast today has the same accuracy as a one day forecast 50 years ago.

Today, forecasters use complex mathematical models to do what is called numerical forecasting. With the numerical forecasting, powerful supercomputers perform complex calculations based on comprehensive data sets. This can be used to generate either short term weather forecasts or a longer term climate prediction. But where does this data come from?

Meteorologists use several tools to measure and gather data. A standard observation station measures temperature, humidity, pressure and detect wind speed and direction.

Furthermore, precipitation radars and satellite pictures are used to get a snapshot of how recipitation and weather systems are placed compared to the weather prognosis. Another important instrument used by forecasters is the radio sonde – or weather balloon. These are one of our most reliable sources of upper-air data.

They consist of a helium balloon attached with a measuring equipment and a transmitter which sends the data down to the earth.

Let's see what happens when I let go of this.

In its two hour trip to the upper stratosphere, – it sends data every second about air pressure, temperature, wind speed and direction and humidity.

There are over 900 launch sites around the world and most of them launch at the same time twice a day. In this way, they can provide data that can be used and shared on a global scale.

We have all been in situations where we ended up disappointed about the weather reports, but let's remember that meteorologists are really trying their best. The weather is just really hard to predict.