What can be used to make weather forectasts like farmers who just look at the sky and say something like "tomorrow it will rain like hell"? Is it really possible to make a forecast just by looking or it is just folkloric hype?

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You can either have your own portable weather terminal, which is a fairly complex set of weather instruments light enough to be carried by any backpacker – bear in mind that they are expensive – or you can learn to forecast based on visual observation.

The first method is of course, the best in terms of precision and reliability because weather terminals are usually linked to the worldwide forecasting networks. In fact, in such a case you will be providing weather data to other terminals and forecasting services. Some people, especially farmers, forest rangers, airfield operators, ship owners and others that depend heavily on accurate forecasts usually purchase and operate this kind of instrumental.

If you are just a backpacker interested in knowing what the weather will be like when you go on hiking, that would probably be overkill so you should learn how to look up, feel the temperature and weather, and make educated guesses. Simple forecasts are not much more than that.

There is a blogpost that you can use as a starting point to learn about meteorology and weather forecasting; you will find it .

Is there actually a way to learn a little bit about forecasting in a structured way? I mean, a course or lessons of some sort.

Certainly: there are all sorts of courses related to meteorology and climatology. You can go to college and become a meteorologist, if you want, or attend seminars, lessons, etc. If you want to become a licensed ship owner / captain or a private pilot, you will indeed learn about meteorology as well.

So, perhaps the best way to learn a bit about the topic if you are interested in attending some sort of course, is to ask someone at your local meteorological office, thorough their website. Be forewarned: while the principles of weather dynamics are exceedingly simple, in practice, weather sciences can become very complicated and the biggest computing power in the world is used indeed, to make our daily forecasts. A lot of math and statistical calculations are involved.

You will also find some articles and comments on meteorology, climatology and weather forecasting .