This is an image of Mt. St. Helens, in Washington, USA.
Click on image for full size
Image from: USGS, courtesy of Volcano World

Volcanoes

Volcanoes erupt when magma from deep below reaches the earth's surface. Once the magma reaches the surface, it is called lava and flows out onto the surface. Some really explosive volcanoes spew out lava fragments, dust clouds, and ash. Most volcanoes exist along plate boundaries and are determined based on its violence and frequency. Volcanoes have a cooling effect on weather because the ash remains in the sky and reduces the amount of sunlight reaching the surface.

Extinct volcanoes have stopped erupting, dormant volcanoes erupt rarely, and active volcanoes erupt frequently.

This is a picture of Mount St. Helens, located in Washington, which last erupted in 1980. It had more amounts of ash than lava. This volcano was the result of two plates colliding into each other.


You might also be interested in:

Surface of the Earth

Most of the Earth's surface (70%) is covered with water, and the remaining 30% is taken up by the seven continental landmasses. However, underneath the water that fills the oceans, and the dirt and plants...more

Pele

Pele is a fire goddess according to the people of Hawaii. She is a savage and wrathful divinity who is said to reside in the crater of the volcano Kilauea. She is considered responsible for all the eruptions...more

Impact Craters on Earth

Compared with other planets, impact craters are rare surface features on Earth. There are two main reasons for the low number of craters. One is that our atmosphere burns up most meteoroids before they...more

Surface and Interior of Earth

Earth, the largest and densest rocky planet, was formed about 4.5 billion years ago. The Earth's interior is divided into four layers, which is typical of rocky planets. Each layer has different characteristics...more

Clouds

Clouds can come in all sizes and shapes, and can form near the ground or high in the atmosphere. Clouds are groups of tiny water droplets or ice crystals in the sky and are formed by different processes....more

How Hurricanes Form

A tropical thunderstorm can grow into a massive hurricane under certain conditions. Sometimes several thunderstorms start rotating around a central area of low pressure. This is called a tropical depression....more

Hurricane Movement

How do we know which way a hurricane will go? Forecasters track hurricane movements and predict where the storms will travel as well as when and where they will reach land. While each storm will make its...more

Storm Surge

One of the most dangerous parts of a hurricane isn’t the rain or the wind. It’s the flooding caused by storm surge. As a hurricane or other tropical storm moves towards a coast, it can cause sea level...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA