How do people predict the weather? These days, by using AI and supercomputers.
People have tried to predict the weather for millennia. When most of the population were involved in the agricultural sector, knowing the weather was important. However, the day to day weather may have been less important than the seasonal weather. If there was a drought, knowing when it might rain would be helpful. Knowing when the frost would come or when the snows would lift were also things that farmers needed to know to plan their crops around. However, it was almost impossible to know and weather prediction was a combination of experience, hope, religion, and witchcraft. Weather prediction only really became possible with the invention of the electric telegraph because you need to know what the weather in other places is doing to predict what the weather where you are will do. The telegraph allowed people to get ahead of the weather and guess at what weather was coming.
Weather prediction is possible because our atmosphere behaves like a fluid. Fluids behave according to certain physical laws, called fluid mechanics. These describe the flow and the movement of any fluid. If you drop something into the fluid at point A, there will be changes at point B. If the fluid at point A is colder than point B, then the fluid at point B is going to want to move towards A. Knowing all of these things can help people work out what the weather is going to do. The trouble is, there are a huge number of variables that need to be taken into consideration. Slight changes in one place can end up making huge changes in another place. So, how do they predict the weather?
The first task is to get as much information as possible. The more data you have, the more likely you will be able to predict the weather. This data comes from commercial planes, ships, research planes, weather stations, mountain stations, satellites, weather balloons, and even people. The data tells them the air pressure, the air temperature, the cloud patterns, the wind patterns, and a whole host of other information.
This is far too much information for people to analyze. Up until the end of the last century, meteorologists, with the aid of computers, would try to analyze the data, but the overwhelming task meant that weather predictions weren’t as accurate as they are today. Since 2000, most weather centers have access to computers with an enormous amount of processing power, and this processing power is increasing year by year. This allows meteorologists to analyze far more data points than before and in a far shorter time frame. However, even with all of that processing power, there is still an element of guesswork.
The computer looks at all of the data and attempts to analyze it using the known physics of the atmosphere and of a fluid. It also has the ability to compare the data to weather patterns that are stored in its memory. From all of this information, the computer makes a prediction on what it thinks the weather is most likely to do. Meteorologists constantly update the information in the computer and tweak the prediction. They then forecast the weather across multiple forms of media. These days, there are also instant weather apps that update all of the time.
All of this sounds wonderful, but it is a lot of guesswork and assumption. Weather prediction is far more accurate than it was even ten years ago, but it is still far from foolproof. There are just too many variables that need to be considered because of the chaotic nature of the atmosphere. If you have a metal bar and you hit one end with a hammer, it is going to move the atoms across the metal bar in a fairly predictable wave pattern. When something happens at one point in the atmosphere, there are a huge number of different directions and ways in which that can have a knock on effect. And the motion of the atmosphere is also affected by the terrain. It takes a supercomputer to be able to analyze so many probabilities, and even then it cannot look at everything.
This is why weather forecasts are less reliable the further away in time they get. The computer can probably predict, with reasonable certainty, if it is going to rain in the next hour. However, it cannot tell you with much certainty if it will rain next week, or even next month. Future weather forecasts are often based on previous weather patterns. In years gone by, when the situation was similar to this, it rained the following week. Past events are not necessarily an indicator of what will happen this time because of the chaotic atmosphere with almost infinite possibilities. And this is what I learned today.
Photo by Genaro Servín: https://www.pexels.com/photo/person-riding-a-bicycle-during-rainy-day-763398/
Sources
https://www.weather.gov/rah/virtualtourfcstobsanalysis
https://wonderopolis.org/wonder/how-do-forecasters-predict-the-weather
https://www.bbc.com/news/explainers-51533852
https://www.metoffice.gov.uk/weather/learn-about/how-forecasts-are-made
https://en.wikipedia.org/wiki/Fluid_dynamics
https://www.ibm.com/weather/industries/broadcast-media/complete-guide-accurate-weather-forcasting
https://en.wikipedia.org/wiki/Weather_forecasting