GEOG220 Lecture Notes - Lecture 9: Shortwave Radio, Jet Stream, Total Pressure
28 Jul 2018
School
Department
Course
Professor
03.06.2018
Reflection, Scattering and Albedo…
- Part of the incoming solar radiation is reflected or scattered by the earth/atmosphere
system
o Radiation is reflected away based on the angle of incidence
- The ratio of the amount of energy reflected by a surface to the amount that is incident on
the surface (the amount that hits the surface) is called the albedo of the surface
o Albedo = 𝑟𝑎𝑑𝑖𝑎𝑡𝑖𝑜𝑛 𝑟𝑒𝑓𝑙𝑒𝑐𝑡𝑒𝑑
𝑟𝑎𝑑𝑖𝑎𝑡𝑖𝑜𝑛 𝑖𝑛𝑐𝑖𝑑𝑒𝑛𝑡
- Earth and atmosphere albedo is about 30% → will be asked on March 20th
- Radiation that hits a surface (or particle) is “scattered” in all directions.
- Why is the sky blue?
o Out atmosphere scatters blue light better than other wave lengths
- Why are our sunsets red?
o It’s the less scattering and red carries through
What Happens to solar radiation as it moves down through the atmosphere?
- This determines the temperature, the weather patterns
o It is CRUCIAL!
- Numbers to memorize
o Earth and atmosphere albedo is about 30% → will be asked on March 20th
o Start with 100% solar radiation
o 5% is scattered back to space from what comes into the atmosphere
o 20% is reflected back to outer space from the clouds
o 5% is reflected from land-sea surface
o 20% of radiation is absorbed by atmosphere and clouds
o On average 50% of short wave radiation makes it to the earth’s surface to be
absorbed
o Net Radiation = SWRd + LWRd – SWRu – LWRu
❖ SWRd (short-wave-radiation) is the incoming solar radiation (after passing
through the atmosphere)
❖ LWRd (long-wave-radiation) is the LWR coming toward the earth from the
atmosphere
❖ SWRu is the solar radiation reflected by the earth’s surface
❖ LWRu is the LWR leaving the earth’s surface
▪ If more radiation is coming in than going out; a radiation surplus
exists… (warming)
▪ If more radiation is going than coming; a radiation defecit exists
(cooling)
❖ Between 35 North to 35 south, we have more radiation going north than south
❖ Above 35 North or below 35 south there is a radiation defecit
- Are the poles constantly cooling down and the equatorial areas constantly warming up?
o NO!
- The earth’s atmosphere and oceans are constantly trying to “even out” these temperature
differences… This is why we have weather!
- Earth – Sun – Relationships are the reasons to why we have these dynamics
END OF CHAPTER 2
Document Summary
Part of the incoming solar radiation is reflected or scattered by the earth/atmosphere system: radiation is reflected away based on the angle of incidence. Earth and atmosphere albedo is about 30% will be asked on march 20th. Radiation that hits a surface (or particle) is scattered in all directions. Out atmosphere scatters blue light better than other wave lengths. Why are our sunsets red: it"s the less scattering and red carries through. This determines the temperature, the weather patterns: it is crucial! Swrd (short-wave-radiation) is the incoming solar radiation (after passing through the atmosphere) Lwrd (long-wave-radiation) is the lwr coming toward the earth from the atmosphere. Swru is the solar radiation reflected by the earth"s surface. Lwru is the lwr leaving the earth"s surface. If more radiation is coming in than going out; a radiation surplus exists (warming) If more radiation is going than coming; a radiation defecit exists (cooling)
