There are over 20 active volcanos left in the world today. Have you ever wondered or learned about what causes a volcano? Volcanic eruptions can be a huge deal for the environment and the people around it. What causes do volcanos have on the environment and what cause does it have on the people? Well the truth is, the causes of active volcanos there are today, do have effects on its surroundings. What is a volcano, and what causes it to erupt? Volcanoes occur at weak points in the Earth 's crust. The outer layer, known as the Lithosphere, of the earth includes the hard crust. The earth is made up of huge plates, these plates shift gradually over a time period of millions of years. The weak points in the crust are located along regions where the plates meet, and also in spots under the sea, these areas are known as 'hot spots '. A volcano is an opening in the earth’s crust often formed like a mountain, which opens downward to a pool of molten rock below the surface of the earth. When pressure is built up inside this pool, eruptions can occur. Volcanoes are formed when magma from underneath the earth 's upper mantle, part of the crust, works its way to the surface. At the surface, it erupts to form lava flows and ash deposits. Over time as the volcano continues to erupt, it will get bigger and bigger because the lava that flows over the top produces a new layer of earth. Lava and ash shoot up through the opening, and burst over the top or fill the air with lava fragments and ash. There have been around 1500 total calculated volcanos since the first recordings in history. Today there remains less than 30 total active in the world now ("Natural Disasters"). What affects to volcanos place on the climate? To start when a volcano erupts, it causes an effect on the global climate. A large number of volcanic ash and volcanic gases are emitted into the air and cause a great impact on the climate. After a volcanic eruption the local weather will be dark
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