Leaf or foliage damage from standing in acidified clouds can be more harmful than having acid rain soak the ground, since the ground will tend to neutralize the acids while the acid cloud droplets damage the means for the plant to manufacture its own food via photosynthesis (see photo below).

An interesting side effect is that forest decline provides a link between acid deposition and global climate change. If large stands of forest are affected by a widespread plume of acidic gases, this may significantly reduce the atmosphere CO2 sink and lead to climate change.

The regions shaded in red are areas of North America that are deemed susceptible to acidification. The black dots and squares are locations of sulfur sources, such as electric power plants. The very middle of the U.S., in Colorado, also used to be a significant source, but Public Service (the provider of electric power) recently converted their power generating plants to natural gas and clean coal processes.

In the northeastern part of the U.S. are the Adirondack Mountains, the location of high-altitude forests.

Brown patches are from acid water droplets burning the leaf.

This is a dead, acid-damaged forest in the Czech republic. This region is directly downwind of the coal-fired power plants in West Germany.