What is the difference between a volcanic ash cloud and a volcanic plume?

A volcanic ash cloud and a volcanic plume are both phenomena associated with volcanic eruptions, but they differ in their composition, behavior, and effects.

A volcanic ash cloud refers to a mass of fine particles, predominantly composed of volcanic ash, that is ejected into the atmosphere during an eruption. These particles are typically less than 2 millimeters in diameter and are formed from the pulverized rock fragments and glass shards produced by explosive volcanic activity. Ash clouds can rise high into the atmosphere, reaching several kilometers in altitude, and can be carried by wind over long distances. They pose significant hazards to aviation as the ash particles can damage aircraft engines, disrupt air traffic, and reduce visibility on the ground. In addition, volcanic ash clouds can also have adverse effects on human health, agriculture, and the environment.

On the other hand, a volcanic plume refers to a column of gases, steam, and other volcanic materials that are expelled from a volcano during an eruption. Unlike ash clouds, volcanic plumes are primarily composed of gases such as water vapor (steam), carbon dioxide, sulfur dioxide, and other toxic gases. The plume rises vertically from the volcano's vent and can extend several kilometers into the atmosphere. The behavior and height of volcanic plumes depend on various factors, including the type of eruption, magma composition, and atmospheric conditions. Volcanic plumes can have regional or global impacts, affecting climate patterns by releasing large amounts of gases and aerosols into the atmosphere. They can also contribute to the formation of acid rain and affect air quality in surrounding areas.

In summary, the main difference between a volcanic ash cloud and a volcanic plume lies in their composition and behavior. While ash clouds consist of fine particles of volcanic ash and can pose hazards to aviation and human health, volcanic plumes are primarily composed of gases and can have broader impacts on climate and air quality.