How do volcanoes affect the atmosphere?
When volcanoes erupt, rocks, ash, and gas rocket into the sky and spread for miles and miles The ash could block out the sun for months at a time. This could affect livestock and other agriculture greatly, depending on the size and impact of the volcano. Some volcanoes can change the whole Earth's temperature by several degrees, causing many changes to the the globe, such as melting glaciers and freezing temperatures in equatorial climates. The "ash" is actually super heated glass shards that are suspended into the air. The gas could also be fatal if it is suspended in the air for too long.
How do volcanoes affect the environment around them?
Volcanic ash blows out as minute particles. When it is inhaled, it can cause coughing and shortness of breath. People suffering from asthma, bronchitis, and emphysema are especially affected by it. Pyroclastic flows are avalanches of molten rock and ash. These flows are very hot and move very swiftly. When towns and cities are engulfed by these pyroclastic flows, almost every sign of life is erased. Livestock like cows and sheep are lost because the ash covers the grass and if the livestock eat this grass, they could die. People living in vicinity of an eruption are at risk of injury and even death by roof collapse. This is because ash particles continually get deposited on the roofs of the dwellings. If the weight increases beyond what a roof can endure, it buckles. There is an upside of volcanic ash, however. Volcanic ash makes the soil in the area extremely fertile.