Alzheimer's disease. Sliced sections from two brains. On the left
is a normal brain of a 70-year-old. On the right is the brain of a
70-year-old with Alzheimer's disease. The right brain is atrophied with a
loss of cortex and white matter. Alzheimer's disease is a dementing
disorder marked by certain brain changes regardless of the age of onset.
It is not a normal part of aging. It is a dementing disorder that leads
to the loss of mental and physical functions. The chance of developing
Alzheimer's increases with age.
Earth's wind patterns, schematic view. Atmospheric circulation in
each hemisphere consists of three cells. The Hadley Cell (labeled)
dominates the tropical atmosphere and is intimately related to the trade
winds, tropical rain belts, subtropical deserts and the jet streams.
The Polar Cell (labeled) produces the polar easterlies. The outflow from
the Polar Cell creates waves in the atmosphere known as Rossby waves
which play an important role in determining the path of the jet stream.
The polar cell also balances the Hadley Cell in the Earth's energy
equation. The Ferrel Cell (labeled) is dependent upon the Hadley Cell
and the Polar Cell and just as the trade winds can be found below the
Hadley Cell, the westerlies can be found beneath the Ferrel Cell.