Do Mountains Really Make Their Own Weather, And If So Why?

When you are in high mountains and watch their glaciated peaks from warm valleys, then the answer to the question in the title seems obvious, doesn’t it? But there is much more to this.

Why and how does mountain make their own climate and weather?

This question can be answered differently for different mountains. It depends on the geography of the larger area, vicinity of seas and oceans, and similar factors. I will give you one example to show the point.

Tenerife climate example

Tenerife island has a very specific climate. Perhaps you did not know, but there is Anaga rain forest in one part of the island. This part of the island is relatively low compared to the rest where you have a very high El Teide volcano. The highest point in Anaga is around 1000 meters above sea level.

However, this Anaga area is very frequently in clouds. They come from the north side and they remain on the north side of Anaga. I had numerous opportunities to be there in clouds. You can hear wind all the time, and the area is always wet. See how it looks, this is from one of my many tours in the area:

But if you walk just a couple of kilometers, once you are on the south slopes, you will see a clear sky with no winds at all. The picture below shows the drastic difference in the local climate, this is Pijaral on the south side of the same area of the Tenerife island:

I stress again, that the distance from these two places is just a few kilometers, and the mountain ridge in between is not at all very high. Yet, its effects are very strong and obvious.

So what happens here can be, roughly speaking, described as follows. Clouds come from the north side and they are counteracted by the warmer air that raises from the south slopes. So clouds start raising up and they circulate, most likely they also cool, and this produces condensation.

When you are there you can be wet all the time even without actual rain. You can hear the “wind”, which is a part of the mentioned vertical air circulation. But move just half an hour walk to the south side and you will have no winds at all.

How do mountains block rain?

I decided to address this question here just because of the text above and those two photos. As you realize, the mountain and the air flows from the south side that raises along its southern slopes, effectively blocks clouds. So they do not pass to the south side. As a result, the Pijaral area shown in the picture above is very dry and with a vegetation typical for such a dry climate.

This is just one simple example which describes what can happen. In much higher mountains, this can result in far more dramatic consequences. Just think about Himalayas, wet areas on their south slopes, and deserts on the north side.

Do mountains create storms? Why do mountains have afternoon storms? 

Here too, I shall again give some practical examples from my own mountaineering experience. I have been in many storms in the mountains, you can see some examples in my text here in the site on what to do if you are caught in a storm in the mountains.

But here, I would add a few lines about the afternoon storms that are in the question given in the subtitle above. This text is not only about mountain weather but also about various “why” in the mountains.

A typical example of such afternoon storms are those in the Slovenian Alps. Have you ever been there? No? Then you must go once. These mountains are lower that in the rest of Alpine countries, but they are very sharp and valleys are narrow and deep.

So if you want to climb there, you will have long tours because your starting point is usually very low in the valley. Locals tend to go early, I can say that I started my mountaineering life there when I climbed Triglav many decades ago, so I have accepted this habit. Some call this an alpine start.

However, this is more than just a habit. If you go early, then you can get to the summit and off the summit before clouds start gathering around. Very soon after that you can have a rain storm.

One typical recent example of that type was my climb to Jalovec. I had a perfect weather, so I was on the summit without clouds on the sky. See how it was, not a single cloud anywhere:

But as I was descending, out of nowhere, clouds where forming around the summit. Here below is the view towards the summit where I was less than 40 minutes ago:

Well, later, when I was at the car and driving back, the summit was completely in clouds and it was raining there heavily. The point is, if there is any chance of storm, you should not be on the summit or anywhere near it. As a rule, you can always have a storm in the afternoon.

Now, why? I am just a physicist and not a meteorologist, so my explanation is that this is because of deep valleys that are also wet and with rivers. They get heated during the day and there is lots of moisture and fumes that raise along the steep mountains’ walls that can be two kilometers high. This all creates clouds around peaks, and then there is rain as the clouds cools at such high elevations.

This all is more or less presented also in this video, please have a look:

Is mountain weather unpredictable?

The short answer is – it is totally unpredictable. This is why I always (and I stress again without exception) have a complete waterproof layer when I am in the mountains.

I also always have gloves and a warm cap in the backpack.

To show you one example, you can read about our tour to Bivacco Battaglione Ortles. You can see the picture of this refuge here in the site in my separate text.

So, in that day-tour we had sunny intervals, rain, snow, and hail. In other words, we had all seasons in one day.

But, there was a question in the title: why this is so? In answer to this, I would stress that these are high mountains, the peaks around are well over 3000 meters, and valleys are very deep. So air circulations are on much larger scales than those described in the previous sections above, related to Tenerife and Slovenia.

So in these Italian Alps, air from the valleys goes to higher elevations as it is directed by the high peaks. It cools rapidly, and this can create rain at lower elevations, and snow and hail at higher elevations. This is exactly what we experienced.

The picture below shows me in that same summer snow storm. But have you seen the top picture above? This is from the same tour.

Do mountains create clouds?

You have seen my short episode about Jalovec described above. I could give you many more examples. So, although the question raised here may sound strange, the answer is yes, in a sense, mountains do create clouds.

What I was describing about Jalovec was all completely local. Those were not clouds that normally come from the north-west, from the Atlantic. This happens all the time as well, of course, but I am talking about a local effect.

So this is about clouds formed from vapor coming from low valleys around, and they cause precipitation that follows after that. Next day, this vapor will raise again and the cycle will repeat.

Summary

In conclusion, mountains can really make their own weather, so this is a local phenomenon and it can be independent from a more global weather situation and area. I gave a few examples in the text above.

You might want to read also my text about getting wet when walking in clouds. If you are curious, there are indeed places where you can get into real clouds.

Thank you for reading. Let me know if I have missed saying something important here, there is a comment box below.

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