Ash particle size usually decreases with distance from vent.

Ash particle size usually decreases with distance from vent....

Detailed Description

The size of ash particles that fall to the ground generally decreases exponentially with increasing distance from a volcano. Also, the range in grain size of volcanic ash typically diminishes downwind from a volcano (becoming progressively smaller). At specific locations, however, the distribution of ash particle sizes can vary widely (see the Mount St. Helens example). (modified from Johnston, 1997)

Details

Image Dimensions: 352 x 251