Pat Arnott, ATMS 749, UNR HOW DO WE TALK ABOUT RADIATION IN THE ATMOSPHERE?

Pat Arnott, ATMS 749, UNR Relationship between Spherical and Cartesian Coordinates

Pat Arnott, ATMS 749, UNR Solid Angle Definition

Pat Arnott, ATMS 749, UNR Irradiance Definition F = Irradiance, (also called flux or flux density), is the electromagnetic energy per unit time, per unit area, transported through dA, or deposited on dA. SI units are Watts/m 2 when integrated over a distribution function F. (Example: solar flux at the TOA is 1360 W/m 2.) F   Monochromatic Irradiance, SI units are W/m 3.

Pat Arnott, ATMS 749, UNR Monochromatic Radiance Definition I = Monochromatic radiance, is the monochromatic irradiance (measured on a surface normal to the beam) per unit solid angle traveling in a particular direction. This is the most fundamental measure we can use for radiation in the atmosphere.

Pat Arnott, ATMS 749, UNR Irradiance - Radiance Relations Upward irradiance. Note ESPECIALLY the cos term (that gets the normal component of radiance) and the sin term (that helps define the solid angle.)

Pat Arnott, ATMS 749, UNR Irradiance - Radiance Relations Special case: I isotropic, same in all directions, like black body radiation from a surface.

Pat Arnott, ATMS 749, UNR BLACK BODY RADIATION AGAIN: RADIANCE Note especially the units of radiance on the left.

Pat Arnott, ATMS 749, UNR ASIDE: EMISSIVITY OF VARIOUS SUBSTANCES

Pat Arnott, ATMS 749, UNR Irradiance - Radiance Relations Downward irradiance

Pat Arnott, ATMS 749, UNR THE BIG PICTURE: Radiation Heating of the Atmosphere From Oort and Peixoto

Pat Arnott, ATMS 749, UNR ATMOSPHERE HEATING BY RADIATION: The heating rate is the divergence of the net irradiance (or net flux if you prefer). From Oort and Peixoto

Pat Arnott, ATMS 749, UNR ATMOSPHERE HEATING BY RADIATION: The heating rate is the divergence of the net irradiance (or net flux if you prefer). From Oort and Peixoto

Pat Arnott, ATMS 749, UNR ATMOSPHERE HEATING BY RADIATION: The heating rate is the divergence of the net irradiance (or net flux if you prefer). This is the figure caption for the heating rate calculation, and the reference. 2 problems: 1. Is the assumption of stratosphere radiative equilibrium good? 2. Is it correct to separate out the LW emission from components? From Oort and Peixoto

Pat Arnott, ATMS 749, UNR Sun and Satellite Perspective: How do the properties of the surface affect what we see?

Pat Arnott, ATMS 749, UNR Radiance and Irradiance: How do we define radiation? Types of reflection: Can also think of the reflected light as emitted light from different types of surfaces.

Pat Arnott, ATMS 749, UNR Geometry for the BDRF (bidirectional reflection function) S is solar irradiance coming in. I is the reflected radiance.

Pat Arnott, ATMS 749, UNR ENERGY BUDGET: 100% in, 100% out. What does it do along the way?

Pat Arnott, ATMS 749, UNR ASIDE: COMPLEX REFRACTIVE INDICES OF WATER AND ICE. Note that the author DID NOT show that the real part of the refractive index for ice at 2.85 microns is less than 1!