Heat Capacities of the Atmosphere and the Oceans

  • Volume of the atmosphere: not really meaningful.
  • Volume of Earth’s oceans: 1.335×1018 m3
  • Mass of the atmosphere: 5.15×1018 Kg
  • Mass of the oceans: ~1.4×1021 Kg
    • Average salinity: 0.035 Kg salt per Kg water, so 3.5% by mass.
  • The oceans are 272x the mass of the atmosphere.
Specific Heat
  • Specific heat of “air” at 250K is 1005 J/KgK
  • Specific heat of ocean water is ~4000 J/KgK
Total Heat Capacity
  • Total heat capacity of the atmosphere: 5.2×1021 J/K
  • Total heat capacity of the oceans: 5.6×1024 J/K
  • The heat capacity of the oceans is ~1,077x the heat capacity of the atmosphere.

I think it’s interesting that the ocean is only 272x the mass of the atmosphere. That is knowable intuitively if you know the approximate pressure deep-sea subs deal with or know that 10m of water is equal to about 1 atmosphere of presure.

Another interesting scale to put in perspective is that the hydrosphere is about 0.023% of Earth’s total mass. So the Earth mass is about the mass of 4,300 oceans.