Question

across

1. one half of earth
2. it takes earth 365.25 days to do this
3. waves used to kill bacteria
4. waves with the longest wavelengths
5. in the northern hemisphere, the sun’s rays are spread out over a greater area

down

1. at the equator, the sun’s rays are concentrated over a small area
2. the angle at which the sun’s rays reach earth’s surface
3. 12 hours of day and 12 hours of night on september 22 or september 23
4. sun’s energy that enters the atmosphere
5. 12 hours of day and 12 hours of night on march 20 or 21
6. a measurement of incoming solar radiation

Explanation:

1. Across - 3: A hemisphere is one half of Earth.
2. Earth takes 365.25 days to complete one revolution around the Sun.
3. Ultraviolet waves are used to kill bacteria.
4. Radio waves have the longest wavelengths.
5. In the Northern Hemisphere (especially in winter), the Sun's rays are spread out over a greater area.

Down - 1: At the Equator, the Sun's rays are concentrated over a small area due to the near - perpendicular angle of incidence.

1. The angle at which the Sun's rays reach Earth's surface is called the angle of insolation.
2. The September 22 or 23 event with 12 hours of day and 12 hours of night is the autumnal equinox.
3. Solar radiation is the Sun's energy that enters the atmosphere.
4. The March 20 or 21 event with 12 hours of day and 12 hours of night is the vernal equinox.
5. Insolation is a measurement of incoming solar radiation.

Answer:

Across - 3: Hemisphere
5: Revolve (around the Sun)
8: Ultraviolet
10: Radio
11: Winter (implied by the spreading of rays in Northern Hemisphere)
Down - 1: Direct (implied by concentrated rays)
2: Angle of insolation
4: Autumnal equinox
6: Solar radiation
7: Vernal equinox
9: Insolation