1. Do Now: How does the Earth get heated?
Why is it warmer in June than in December?

2. Learning Objective:
I will be able to explain how the earths surface is heated.

3. Success Criteria:
I can explain how the angle of insolation impacts the earths surface temperature.
I can explain how earths shape impacts the angle of insolation.
I can explain why temperatures vary throughout the day.

4. Insolation and the Earth’s Surface

5. Insolation- The portion of the Sun’s radiation that reaches the Earth
Angle of insolation (incidence)-
Angle at which insolation strikes the Earth’s surface
The intensity of insolation (how strong) increases as the
angle of Sun approaches 90o
Where the Sun’s rays are vertical (90o), the maximum amount of solar energy is received

6. As angle of insolation increases the intensity of the sunlight increases

7. Angle of insolation varies with:
Seasons - Maximum insolation for New York occurs on June 21.

9. Angle of insolation varies with:
Seasons - Maximum insolation for New York occurs on June 21.

10. Absorption of insolation varies due to:
Water - better reflector
Land - better absorber and radiator
2. Water - higher specific heat than land
(needs more energy to raise it’s temperature)
3. Water - highly transparent: insolation is absorbed at a greater depth.

11. Absorption of insolation (cont):
4. Convection can occur in water distributing the energy
5. Ice and snow reflect almost all insolation
6. Melting of snow and evaporation of water transform insolation into potential energy (keeps temperatures lower)
Energy used for Transpiration – process by which plants release H2O vapor into atmosphere

12. EARTH’S SHAPE- The sun’s energy reaches the
Earth’s surface as parallel rays.
The Earth nearly spherical causing insolation to be spread out over larger area of Earth’s surface

13. LATITUDE- As degree latitude increases insolation decreases
The lower the latitude the higher the angle
90oN
23.5oN 0o
23.5oS
90oS

15. TIME OF DAY- maximum insolation at solar noon
(sun is at it’s highest point - usually around 12:00 p.m.)

16. Daily Temperature Lag-
The time of the highest temperature lags behind the time when the most intense insolation is occuring.

17. Annual Temperature lag-
Annual Temperature lag- -the average warmest day of the summer occurs in late July, around a month after the longest day of the year.

18. Duration of insolation – how many hours of daylight
- Affected by Latitude and Season
Maximum duration in NY (15 hours) on summer solstice.
Average duration (12 hours) on equinoxes.
Least duration in NY (9 hours) on winter solstice.