overall cooling of Earth.YELLOWSTONE CALDERA: The Yellowstone Caldera is located in
Yellowstone National Park (Wyoming) and measures about 34 by 45 miles
(55 x 72 km). Supervolcanoes represent the second most globally cataclysmic
event—next to an asteroid strike—and they have been responsible in the past
for mass extinctions, long-term changes to the climate, and shorter-term
“volcanic winters” caused by volcanic ash cutting out the sunlight. The last
known supervolcanic eruption occurred about 70,000 years ago in Indonesia
and caused a volcanic winter that blocked out the sun for eight years and
resulted in a period of global cooling lasting a thousand years. The
Yellowstone supervolcano last erupted about 600,000 years ago, sending more
than 240 cubic miles (1,000 km^3 ) of ash and lava into the atmosphere—about
100 times more than the Mount Pinatubo eruption. It could erupt at any time.SOLAR INTENSITY, SEASONS, AND LATITUDE–
LONGITUDE
Solar Intensity
Factors that affect the amount of solar energy at the surface of Earth (which
directly affects plant productivity) include Earth’s rotation (once every 24
hours), Earth’s rotation around the sun (once per year), the tilt of Earth’s axis
(23.5°), and atmospheric conditions.
Summer (the period of greatest solar radiation) occurs in the Northern
Hemisphere when the Northern Hemisphere is tilted toward the sun. The sun
rises higher in the sky and stays above the horizon longer, with the rays of the
sun striking the ground more directly (at less of an angle).
Likewise, in the Northern Hemisphere winter, the hemisphere is tilted away
from the sun. The sun rises lower in the sky and stays above the horizon for a
shorter period, with the rays of the sun striking the ground at a greater angle.