2. LEARNING OBJECTIVES:
To be able to reason out why there is a varying rates of surface insolation.
To analyse the factors which contribute to solar heat balance of earth and atmosphere.
Radiation, absorption, reflection, convection, conduction.
LEARNING OUTCOMES
ALL: students are able to reason out how the rates of insolation decreases with latitude from
equator to poles.
MOST: Students are able to differentiate between long and short wave radiation.
SOME: students are able to evaluate and justify the impact of different factors acting on the
climatic condition of the place.
3. The sun as an energy source
The atmospheric system-absorption and reflection
4.
5. What is the difference between short wave and long wave radiation?
6. Insolation
Insolation is the amount of solar energy reaching the Earth’s surface that is
available as heat.
Rates of insolation vary greatly from place to place, the main control is latitude.
7. The heat energy that is radiated is of long wavelength, which is readily absorbed
by water vapor, water droplets (clouds), and carbon dioxide in the atmosphere.
These in turn are heated up by the absorption and themselves radiate heat in all
directions, much of which is re-radiated back to the surface.
Why night temperatures are higher on cloudy nights comparatively to clear
nights?
8. : insolation, absorption, radiation ,conduction and convection.
Students in groups are going to plan a backdrop for Shakespeare play and explain how they
can plan and show the above effect.
9. Home learning:
Discuss with your parents any changes they feel in insolation for the last 10 years. Can support
with news reports.
15. Activity
1-Draw a divided bar graph to show what happens to 100% of light energy radiated from the
sun.
2-Describe how clouds cover affects surface temperature
(a) during the day
(b) at night
(c) overall
3-Draw a scatter graph using the data in Table 1 to show the relationship between latitude and
temperature of the coldest month. Place latitude on the x axis and temperature on y axis.
4-Explain why rates of insulation are different between the tropical and polar latitude.
16. Why insolation is greater at the equator and in the tropics?
The sun’s light has a direct path through the Earth’s atmosphere and less is lost
by reflection. Because the Sun rays are vertical when they strike the surface,
each ray has a smaller area of surface to heat up.
17. Why Insolation is smaller near the poles?
Near the poles the sun’s rays approach the Earth’s surface at an oblique angle,
so that each ray has a larger surface area to heat up. More of the light is
absorbed and reflected, which leaves less to be used for heating up the surface.
18. Why costal cities are cooler in summer than those situated further inland?
This is because the sea does not heat up as quickly as the land since light rays
penetrate more deeply into the water and currents distribute the heat. Breezes
from the sea, therefore, are cooler than those from the land.
Why snow covered regions are the coldest places on the Earth?
A high proportion of the Sun’s light is reflected instead of being absorbed. 80%
of the light that reaches the surface is reflected back from snow covered
surfaces. Therefore snow has a high albedo.
19.
20. Why do we have varying differences in length of days and night in different places of the world.
