Mountains

What a view! Yeah, but I’m cold. I need an extra sweater. If you climb a tall mountain, you’ll discover it gets colder and colder the higher you get. Every 100 metres you climb, the temperature drops about one degree Celsius.

So if you climb 1000 metres, it’s about ten degrees colder than where you started. This makes the climate on tall mountains different than in the lower areas nearby. Mount Kilimanjaro in Africa is situated close to the equator. Nearby there is warm savannah and rainforest, yet there is always snow at the peak of Kilimanjaro, and this is exactly because the temperature decreases the higher you get. And that the temperature decreases with the height, in turn has another effect.

Watch! Here is air moving toward a mountain. It’s windy, and the shape of the landscape forces the air higher. There it is colder - remember? - and when air gets colder, clouds are formed by tiny, tiny droplets of water. Soon, it starts to rain.

Often it rains, or snows, a great deal in mountainous areas. But how did the mountains get there in the first place? Well, mountains can emerge in two ways. One way is the way Kilimanjaro formed. It was created by volcanoes.

Vast amounts of molten rock, magma, was hurled out from the core of the earth. When the magma entered the air it cooled off, solidified, and became a large pile of stone - a mountain. The other way is when the land areas of the earth, continents, collide. Yes, really. The continents move.

It happens slowly, and you cannot see it, but it’s happening all the time. The core of the earth is hot. There, the bedrock is molten and everything floats around. The solid land you walk upon is the surface of the earth. It is a thin layer called the crust.

The crust consists of plates floating on top of the magma. Sometimes the plates collide, and - watch! - parts of the crust are pressed upwards in the air. Mountains are formed, and since they follow the border between continental plates, the mountains form a line. We call it a mountain range. This is how the world’s highest mountain range was created.

The continent of India collided with Asia. This collision started about 50 million years ago and is still going on. It takes millions of years for mountains to form. It’s time for Kim and Philip to descend from the summit. At the top where the air is chilly, not many plants thrive.

The cliffs are bare. Further down where it is not as cold, we find some vegetation. Mosses, heather and low bushes. But no trees. All of a sudden, Kim and Philip reach a forest.

Just a second ago there were no trees at all, and now - wood? They’ve passed the treeline. Often this line is distinct, just as it is here. Above the treeline, not many trees can survive; below the treeline, the forest can quickly become dense. And there, in a glade by the stream, is Philip and Kim’s tent.

Today’s hike has come to an end. Know what? I’m on top of the world now! No, you’re not. You’re in a valley.