3B Light Availability of Phytoplankton Flashcards
what are the main reasons light reaching the earth varies
latitude
season
time of day
day length
atmospheric conditions
how does latitude impact light reaching earth
poles receive less solar energy cus sun is on horizon, therefore larger impact patch
impact patch
solar rays hitting the earth
smaller impact patch means more solar energy per unit area (vice versa)
how does season impact light reaching earth
tilt of the earth causes size of impact patch to change
summer/winter solstice receives most solar energy at 23.5 degrees N/S
what is the is the tilt of the earth’s rotation axis
23.5 degrees
how does time of day impact light reaching earth
maximum solar energy occurs at noon when it is directly over head
function of time of day for the Equinox
how does day length impact light reaching earth
longer days get more sun; more solar energy
poles in summer have longer days and vice versa
what is one mole of photons called
Einstein (E)
what is photosynthesis dependent on
number of photons in the right wavelength reaching the chlorophyll
what is heating in the water column dependent on
light’s energy (short wavelength heats more)
what do we usually use to measure light
irradiance Watts (Joules/s)
watt is the conversion between Watt and Einsteins usually
1 Watt = 4.4 microE/s
what is low, optimal, and high light for a phytoplankton
< 100 microE/m^2 s
150-200 microE/m^2 s
2000 microE/m^2 s
how does atmospheric conditions affect amount of light reaching earth
clear sky lets more light in vice versa
scattering, absorption prevent light from reaching the surface
what percent of solar radiation reaches the surface on a clear day
80
what percent of solar radiation reaches the surface on a cloudy day
25
what is albedo
fraction of light reflected from a surface
average sinced different wavelengths reflect differently
large for light surfaces, vice versa
what does ocean water albedo depend on
surface roughness
sun light angle
sediment concentraion
chl concentration
do open ocean or coastal ocean have higher albedos
coastal oceans
what happens to light as it moves through water
phons scatter/ get absorbed
what is the attenuation coefficient
measure of how clear the water is
larger k is coastal water
what wavelengths does water absorb more
longer wavelengths
what kind of light is found in deeper water
blue
what is photosynthesis
fixation of CO2 into sugars
releases O2