Update week 5 lecture

[ryoliver]

• Should bring in/mention radiative transfer modeling
• Atmospheric windows were confusing, add in graphics

Questions that came up: how does albedo relate to reflectance? the albedo of an object is the proportion of sunlight that it reflects back. remember back to our slide with reflectance of different materials -- snow reflects a large amount of light in many wavelengths compared to other materials, such as water, and therefore has a higher albedo. why is the sky blue and sunsets red? here is a pretty detailed video explainer. a couple of main takeaways: (1) you only perceive colors if the photons of that wavelength reach your eye. (2) because blue is scattered more than other wavelengths, blue photos are more likely to reach your eye. (3) sunsets are red because the sun angle at the end of the day means more blue has been scattered away and red light is more likely to reach your eye.

why does water vapor absorb some wavelengths and not others? huge thanks to all the help from the audience! I think we basically got to the answer in class, but in the case of water vapor there are a couple of things going on… (1) there are three transitions that can take place that lead to absorption (rotational, vibrational, and electronic), each of which has quantized states (i.e. no intermediate state) which give those on/off patterns. (2) different transitions are responsible for absorption of different wavelengths of electromagnetic radiation

how do we know the reflected light didn't change wavelength? we don't! we just define reflectance that way. remote sensors measure radiance reaching the sensor and then there's a lot of work to figure out the proportion that was reflected. this is done through radiative transfer modeling, which is basically a way to estimate reflectance by taking into account all the other processes we discussed (i.e. the overall radiation budget). this is why it's important to know the other processes (absorption, scattering, refraction) that could be changing the radiation that makes it back to the sensor

[ryoliver]

can we include raster/vector interactions? save scattering conversation for following week?

[ryoliver]

Reflections from 2024:

• ended up not quite filling time
• scaled back the lecture to skip scattering
• add brief raster/vector interaction

Ideas for updates:

• is there more fundamental RS to include? radiation budgets?
• or could add more raster/vector interactions