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EAS 212 > Lecture 3 > Flashcards

Lecture 3 Flashcards

1
Q

How are deep currents mapped

A
  • they are mapped using subsurface floats

- >floats can float to a particular water depth or density to follow a mass

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2
Q

Describe the characteristics of subsurface floats

A
  • can be set to float at a given depth
  • > can also be specified to float within a given density surface to follow a water mass
  • > returns to surface at intervals to send information
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3
Q

Describe the Argo program

A
  • an international collaboration
  • > since the year 2000
  • > collects temperature and salinity profiles from the upper 2000 m of the ice-free global ocean

-also collects currents from intermediate depths using profiling boats

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4
Q

How does the Earth interact with short-wave radiation and long-wave energy

A

-earth is heated by visible short-wave radiation from the Sun and cools by radiating infrared(long-wave) energy back to space

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5
Q

What are the three things that Earth’s temperature depends on

A
  • depends on the amount of incident sunlight, the planet’s reflectivity, and the greenhouse effect on the atmosphere
  • note the radiation from the sun is absorbed on the planet by materials on the earth’s surface like rock and water
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6
Q

What is the proportion of the wavelengths of energy received from the Sun to the Earth

A
  • 50% of energy is in the visible range
  • 40% is the infrared radiation
  • 10% is in the UV radiation range
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7
Q

What is the solar constant

A
  • average energy flux from the sun at the mean distance of Earth
  • > the amount of energy that a planetary body would be receiving from the Sun
  • the Earth receives about 1366-1368 W/m from the Sun
  • > as the Earth’s orbit is elliptical, not circular, this energy varies by 3.5% seasonally
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8
Q

What is solar incidence

A
  • it is the total amount of solar energy that can be absorbed by the Earth
  • > Solar Constant(S) x cross-sectional area(“flat” area of the Earth)
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9
Q

What is the total power of sunlight hitting the Earth

A
  • that is the solar constant multiplied by the area of a circle
  • > this power is distributed over the Earth’s entire surface
  • > around 344 W m^2
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10
Q

Is the amount of solar energy that hits the Earth from the Sun 344 W x m^2

A
  • no
  • > because not all this energy is absorbed
  • > a fraction(albedo) is relfected or scattered
  • > an average albedo for the globe is 0.30
  • > thus, actual solar energy received is 238 W x m^2
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11
Q

What does albedo mean

A
  • the fraction of the sun’s radiation that is reflected from the surface
  • > about 0.3 or 30%
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12
Q

Is albedo greater at higher altitudes or lower altitiudes

A
  • it is higher at altitiudes
  • > because there are more reflective surface like snow and ice

-lower latitude like equator have low albedo because of less reflective surfaces

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13
Q

What is the Earth’s energy budget controlled by in terms of incoming radiation and outgoing radiation

A

Incoming(solar irradiance)

  • > temperature of the sun
  • > distance from the sun

Outgoing Radiation

  • > Earth’s reflectivity(albedo, A)
  • > Radiated energy(blackbody radiation)
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14
Q

Describe the term Blackbody radiation

A
  • a blackbody emits and absorbs radiation with 100% efficiency at all wavelengths
  • > most objects behave similarly to blackbodies
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15
Q

How would you describe through a formula the energy received and reflected by the Earth

A

Energy received
->piR^2 x S

Energy reflected
->piR^2 x S x A(albedo)

-difference between energy received and energy reflected is the energy absorbed

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16
Q

What is the main greenhouse gas in the atmosphere

A
  • it is water vapor

- >but there are other greenhouse gasses like carbon dioxide and methane which gets more attention

17
Q

What is the net heat flux made up of

A

-it is made up of short waves(incoming solar radiation), long waves(infrared radiation reflected back), sensible heat and latent heat

18
Q

Describe sensible heat

A
  • flux of heat due to conduction
  • > heat gained or lost by a body resulting in a change in temperature with no phase change
  • direct physical contact between the atmosphere and the oceans leads to energy change by conduction
  • > energy is transferred to the cooler molecules by molecular collisions

-note sensible heat is something that we can measure, touch or feel

19
Q

What are the two factors that sensible heat flux depends on

A

-it depends on the local air-sea temperature difference and wind-speed

20
Q

What is latent heat

A
  • the hidden heat
  • > not sensible, something we are measuring
  • when water is evaporated, energy is supplied to the molecules to free them from the strong bonds in the liquid water
  • when water molecules condense to form droplets, energy is released in the form of heat
  • latent heat is very specific to phase changes
21
Q

Does water have a very high heat capacity

A

-yes

22
Q

Is heat exchange latent in polar regions? What does this mean?

A
  • yes

- >this means that the ocean temperature changes very little over the course of the year

23
Q

Why is the high latent heat of vaporization importaant for atmospheric heat transport

A
  • head is added in the tropics
  • > this warms the water and leads to evaporation
  • > this heat is stored in water vapor molecules, which are blown to higher latitudes, where they condense as rain
  • > the heat in these water molecules is released to the atmosphere, warming the higher latitudes
24
Q

Is the incoming solar radiation evenly divided over the Earth

A
  • no
  • > there is a net surplus of radiation in the tropics and deficit at the higher latitudes
  • > this leads to a transport of heat by the oceans and atmosphere from the equatorial regions to the poles
25
Q

How does angle of impact of solar radiation play a role in the latitudes

A
  • sunlight strikes at a high angle for the low latitudes
  • > therefore, radiation is concentrated in a small area

-sunlight strikes high latitudes at a low angle so same amount of radiation is spread over a larger area

26
Q

How does the atmospheric path length affect the amount of sunlight received at the latitudes

A
  • Earth’s atmosphere absorbs some radiation
  • > less radiation strikes Earth at high latitudes than low latitudes
  • > because sunlight passes through more atmosphere at high latitudes
27
Q

How does the differing albedo at different latitudes determine the amount of sunlight received

A

High albedo at the higher latitudes due to reflective surfaces(ice)
->therefore, the surface reflects the majority of radiation that hits it

Low albedo at the lower latitudes due to less reflective surfaces
->therefore, the surface absorbs majority of the radiation that hits it

28
Q

What influences seawater temperature and salinity

A
  • solar radiation
  • transfer of heat and water with the atmosphere
  • ocean currents
  • vertical mixing
  • runoff

EAS 212 (7 decks)

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