Things are Starting to Heat Up - Part X 13

[dik]

For earlier thread, see:

thread1618-496010
thread1618-496614
thread1618-497017
thread1618-497239
thread1618-497988
thread1618-498967
thread1618-501135
thread1618-504850
thread1618-506948

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[SwinnyGG]

How does climate change explain the warming of the oceans?

I know I'm wasting my breath here, but it's really not very complicated.

The ocean absorbs the visible light emitted by the sun. 1360 W/m² average just like everywhere else. It then radiates energy back out, but not in visible wavelengths - the emitted energy from the ocean is in the infrared band. This is fairly obvious since when you stand on the edge of your tugboat and look down at the water you aren't blinded by the glowing ocean.

CO₂ both absorbs and emits in the infrared band. Infrared energy absorbed by a CO₂ molecule is re-emitted in all directions - meaning that on average, 50% of the energy absorbed is re-emitted back toward the earth.

Most pure gasses, such as and including N₂ and O₂ don't absorb infrared. If there were no greenhouse gasses at all in the atmosphere, 100% of the infrared energy emitted by the ocean (and the land, too) would pass right through the atmosphere into space, and the planet would be very cold.

As the percentage of gasses in the atmosphere that absorb and re-emit infrared back toward the surface instead of letting it pass by into space goes up, the total quantity of infrared energy being radiated toward the surface increases, and the percentage of the total energy absorbed by the planet which is allowed to radiate off into space goes down.

More energy radiated toward the surface of the planet means more heat absorbed, which means higher temperatures. Not very complicated.

 

[dik]

Thanks for a better explanation of 'trapping the heat'. Your explanation was a lot shorter than mine would have been.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[waross]

As a boy I swam in Okanagan lake.
The sunlight heats the water up to a depth of about 4 or 5 feet.
Convection works to keep a fairly sharp division between the heated water and the cooler water beneath.
Wind and waves worked to mix the upper warm water with the lower, cooler water.
Water temperatures on the beaches often reached 80 F.
During hot, still weather the local radio station regularly broadcast the beach water temperature.
When there were days of clear skies and no wind, the water would heat up.
It didn't take much wind to create enough wave action to mix the water and drop the temperature of the upper layer.

Warmer than usual ocean water?
Usually correlates with days of clear skies and little to no wind or waves.

By the way, I still remember the feeling of diving into 80 degree water and at a depth of 4 or 5 feet, feeling my body pass into the much cooler water below.
It was a unique feeling as the sharp division between warm and much cooler water passed over your body as you dove down into the cooler water.
Today:

Water temperature in Okanagan Lake is expected to rise to 25°C in the next 10 days. July average water temperature in Okanagan Lake is 24°C, the minimum temperature is 20°C, and the maximum is 30°C.

By the way, while many beaches are fairly shallow shelves. the lake is a very deep lake.

--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[BridgeSmith]

Thanks, waross. I couldn't wrap my mind around the 100 degree ocean temps; that's like hot tub temps. If it's only the top 5 feet or so, I guess I can buy that. The water in the bays in Jamaica were warm when I was there, but not close to being that warm.

 

[TugboatEng]

SwinnyGG, the water has 1000x the heat capacity x volume of air. If what you described is the only cause of ocean heating then it should occur 1000x more slowly than the atmosphere.

 

[dik]

...maybe it's heating that fast; could that be a reason for concern?

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[SwinnyGG]

water has 1000x the heat capacity x volume of air

Yeah.. which is why fractional degrees of change in the average temperature of the ocean represent very large changes in the total thermal energy stored by the earth and available to warm the atmosphere.

If what you described is the only cause of ocean heating then it should occur 1000x more slowly than the atmosphere.

Wrong.

'Air' is not a homogeneous material. Each of the constituent gasses have a different response to solar radiation. They are not uniformly heated by the same exposure. What we now call 'greenhouse' gasses representing a small volume percentage of the atmosphere, but represent a dominating percentage of the heat absorption. The heat absorbed by these molecules is transferred to the other gasses. In other words, of the entire volume of the earth's atmosphere, a very small percentage is actually absorbing heat- meaning that of the total radiant energy passing through the atmosphere, only a small percentage is absorbed.

Water is, relative to the atmosphere, a homogeneous material. All of the water that is directly contacted by solar radiation has the same response, and 100% of solar radiation across all wavelengths that hits the water and is not reflected is absorbed.

Point is, the ocean absorbs a much larger percentage of the energy radiation onto its surface than the atmosphere absorbs of the radiation passing through it.

The stuff I'm talking about in this post and in my last post are settled physics. Whether you believe humans are warming the planet or not, the earth's energy balance is very well understood. Settled science.

 

[TugboatEng]

Ok, CO2 absorbs the reflected radiation which causes the greenhouse effect. It's not reflecting the radiation back. CO2 should have no impact on how much radiation is reaching the oceans's surface. The heating of the oceans cannot be a result of greenhouse gasses if the ocean is exclusively heated by radiation.

 

[SwinnyGG]

Ok, CO2 absorbs the reflected radiation which causes the greenhouse effect. It's not reflecting the radiation back. CO2 should have no impact on how much radiation is reaching the oceans's surface. The heating of the oceans cannot be a result of greenhouse gasses if the ocean is exclusively heated by radiation.

Wrong.

It's not reflecting anything, and no one said it was. For the second time:

CO₂ molecules absorb infrared, which is then re-emitted. 50% of the re-emission is back toward the earth. Of the infrared radiation coming from the surface that DOES NOT hit a CO₂ (or other greenhouse gas) molecule on its way toward the edge of space, 100% of that energy escapes. Of the infrared radiation coming from the surface that DOES hit a CO₂ (or other greenhouse gas) molecule on its way toward the edge of space, 50% of that energy is re-emitted back toward the surface. More CO₂ (or other greenhouse gas) molecules in the atmosphere means a higher rate of radiant flux on the surface. Period. Settled physics. If you debate this you are arguing against known facts and demonstrating that you have no clue what you're talking about.

 

[TugboatEng]

If 100% of the solar radiation that impacts water is absorbed, not reflected, what reflected infrared radiation is the CO2 above the oceans reflecting back down to the oceans?

 

[waross]

If 100% of the solar radiation that impacts water is absorbed, not reflected,

That's not what I heard him say.

--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[TugboatEng]

Yes, I see now that is not exactly what he said.

However, would radiation reflected once not be reflected again?

 

[SwinnyGG]

However, would radiation reflected once not be reflected again?

You need to stop using the term 'reflected' to describe an absorption/re-emission process. They are fundamentally different.

And, generally, no. The radiation absorption spectrum of water has a gigantic peak in the IR band. The IR emitted by the water, absorbed by the CO₂, and re-emitted back toward the ocean surface is almost completely re-absorbed again.

This is the absorption band for liquid water at 25⁰C. Notice the valley in the visible band, which allows water to be transparent. Note how the lowest absorption value on the whole plot is right over the blue part of the visible band. This is why when you're deep underwater everything is visible in shades of blue only - all other wavelengths are absorbed.

Then notice the giant absorption values in the UV and IR bands.

 

[TugboatEng]

Does the wavelength of absorbed and re-emitted IR change or is it re-emitted at the same wavelength?

Edit: I am reading that CO2 most strongly absorbs at the 15um wavelength and so does water so it falls back to water not reflecting much IR. This means the oceans would see less effect from the greenhouse effect.

 

[SwinnyGG]

Does the wavelength of absorbed and re-emitted IR change or is it re-emitted at the same wavelength?

It depends on conditions such as the vibration state of the molecule when the IR photon is absorbed, the temperature, etc.

This means the oceans would see less effect from the greenhouse effect.

Uh, no. It does not mean that.

The IR that CO₂ molecules absorb is re-emitted. It is not captured forever. An IR photon strikes a CO₂ molecule and its energy changes the vibration state of that molecule. Which vibration state results depends on a bunch of factors that don't matter in this discussion. After some small period of time, the CO₂ molecule will return to its base vibration state- and when that happens it emits an IR photon that can be at any one of several wavelengths depending on again a bunch of factors that don't matter for the scope of this discussion.

Less IR escaping the atmosphere means warmer water. Period. Settled. There is no debate. It's simple physics. The fact that it blows up your political point of view on this issue, that you don't understand and don't care to take the time to understand, or that you just don't like it absolutely does not matter. It is a physical reality of the universe we occupy. The fact that continue to argue this point is just continuing to demonstrate that you are out of your depth, and are motivated solely by your politics. Give it up.

 

[dik]

The seem to be heating up a tad... should they be heating up more?

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[dik]

...continued in

thread1618-510266

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik