METR112 Homework Assignment 2
Due October 9
1. What is short and long wave radiation, and why does the Sun emit more
shortwave radiation than the Earth (15 points)?
shortwave radiation The radiation received from the sun and emitted in the spectral
wavelengths less than 4 microns. It is also called 'solar radiation'.
longwave radiation The radiation emitted in the spectral wavelength greater than 4
micrometers corresponding to the radiation emitted from the Earth and atmosphere. It
is sometimes referred to as 'terrestrial radiation' or 'infrared radiation,' although
somewhat imprecisely.
Source: NASA Earth Observatory Glossary
http://earthobservatory.nasa.gov/Library/glossary.php3?mode=alpha&seg=l&segend=n
The Sun emits more solar radiation than the Earth because it has much higher surface
temperature than the Earth.
2. How would the earth’s radiation budget change if the Earth’s albedo were to
increase or decrease (15 points)?
If everything else doesn’t change, an increase in albedo will reduce surface
temperature, and consequently, reduce surface longwave radiation emission.
3. Why do we have seasons? Do you understand why the number of sun hours
changes with season (15 points)?
We have seasons because the Earth rotates around its axis and revolves around the
Sun at the same time. The Earth's axis is tilted at an angle of 23.5 degrees. The tilt of
the Earth means the Earth will lean towards the Sun (Summer) or lean away from the
Sun (Winter) 6 months later. In between these, Spring and Autumn will occur.
Therefore, the Sun light reaches different areas of the Earth at different angles.
See http://www.woodlands-junior.kent.sch.uk/time/seasons.htm
4. How is a cloud different from water vapor (20 points)?
Cloud differs from water vapor in many ways:
a. water vapor is gas, and cloud is either liquid or solid (iced cloud droplet)
b. water vapor has greenhouse gases, so it warms surface; clouds has
warming and cooling effects
5. How can clouds affect the local temperature? Draw a figure to show (20 points).
Clouds warm the surface via albedo effect (reflect solar radiation)
Clouds cool the surface via greenhouse effect
Figure --discussed in class
6. What is the carbon cycle. Why is it important to climate change (15 points)?
 The complex series of reactions by which carbon passes through the Earth's
–
Atmosphere
–
Land (biosphere and Earth’s crust)
– Oceans
Carbon is critical since CO2 affects climate change.