midterm 2 Flashcards
Why does Earth have seasons?
- b/c its axis is tilted as it moves around the sun.
- earth rotates 24 hours
- earth takes 365 days revolution around the sun.
maintain angle of tilt 23.5
When is Earth closest to the Sun in its present orbit? How does this “close pass” position affect the amount of radiation received on Earth?
earth is (closest) to sun on (perihelion) on January 3.
This is more radiation. The distance of 147 million kilometer from the earth.
as it moves fastest during perigee the solar day would be largest. Whereas the solar day the solar day wold be smallest during apogee( aphelion = is away on July, 4 ) because the earth moves much slower at this position.
when earth is in aphelion it receives less radiation from sun and temperature would be the lowest.
Earth’s tilt is slowly decreasing today. As it does so, are the Polar Regions receiving more or less solar radiation in summer? In winter? How can these changes in the seasonal amount of solar radiation affect climate?
earth tilt decreases, the poles would be away from sun during (summer). less radiation in the summer.
during the (winter), the poles will be directly towards the sun. they would receive more solar radiation.
How is axial precession different from precession of the ellipse?
Axial precession is the wobbling motion of the earth caused by the gravitational pull of sun and moon causing slight bulge in the diameter of the earth at the equator. 23.5
precession of the eclipse( precession is slower) is the entire elliptical shape of earth orbit tends to rotate. It is slower in space.
*the combined motions of these precessions leads to the occurrence of equinoxes( twice a year, march, & September same length day&night). and solstices (revolution around sun .
What is the precession of the equinoxes?
movement of solstices around Earth’s elliptical orbit over cycles of 23,000 and 19,000 years
How does eccentricity combine with precession to control a key aspect of the amount of insolation Earth receives?
both combine would result variations of distance between earth and the sun by the seasons with the cycle of 23,000 years. solar radiation is more on perihelion and less on aphelion.
the high eccentricity would result in large contrast in the distance between the earth and sun low eccentricity would result in low contrasts.
During each Earth’s annual revolution around the Sun:
Earth maintains a constant angle of tilt.
The main role of eccentricity in long-term changes in solar radiation is to
magnify or suppress contrasts in Earth-Sun distance during the precessional cycles
What is TRUE about the level of summer insolation in the Northern Hemisphere TODAY?
It is well below the long-term average.
When Earth’s tilt is close to its smallest value,
there is the lowest summer insolation in the Northern Hemisphere.
When is Earth farthest away from the Sun in its present orbit?
during the Northern Hemisphere’s summer
The tilt of Earth’s axis TODAY is:
slowly decreasing
If Earth’s axis had no tilt:
the direct solar rays would always strike at the equator.
Monsoons are stronger
where there are large landmasses adjacent to oceans.
Where is the most powerful monsoonal circulation TODAY?
South Asia
Which of the following has the greatest effect on ice sheet growth or melting?
accumulation of snow in the winter
How does bedrock respond to a heavy ice load?
Bedrock responds with immediate fast sinking which later slows down.
How thick must an ice sheet be to depress the underlying bedrock by 1 kilometer?
3 kilometers
How does ice retain a record of past atmospheric gas composition?
in air bubbles trapped within glacial ice
Which isotopic transfer occurs during glaciations?
C12-enriched organic matter is transferred from land to the ocean
How did changes to ocean waters during the glaciation affect the level of atmospheric CO2?
Cooling of the surface and deep ocean increased the solubility of CO2 and reduced atmospheric CO2.
Where is most natural methane CH4 produced?
in swamps and bogs
