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Ishmael
In: Toronto
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Ahhh... a significant question!
There is an answer.
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Hatty
Site Admin
In: Berkshire
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On the subject of precipitation, there was an intriguing piece about seaweed influencing cloud formation ('Material World', Radio 4)
A recent study has found that large brown seaweed release a form of iodine to protect itself from intense sunlight or low-lying atmospheric ozone, causing clouds to form.
Iodine has been extracted from seaweed for centuries for medical use but now scientists are trying to understand the influence of iodine compounds emitted by seaweed on the local climate which seems to have a cloud seeding effect. Most types of seaweed contain iodine, the largest concentration was found in kelps (laminaria digitata in particular) where it can make up to 5% of the kelp's weight (they don't know why so much iodine is manufactured, one theory postulates a defence against predators but iodine can be almost non-toxic).
Experiments conducted on the west coast of Ireland found that particles were emitted into the atmosphere only during the daytime and they found a pattern between tidal levels and atmospheric content, an increase in amount at low tide and a decrease at high tide. The explanation put forward is that since ozone is potentially harmful (high level ozone as we know affords protection from UV rays but low level ozone is toxic) the iodine particles protect the kelp against ozone toxicity by reflecting sunlight, i.e. away from the seaweed. With a low concentration of particles, less clouds form and a high number of particles can lead to thicker clouds forming.
It's not yet fully understood. "More research needed."
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| Ishmael wrote: | | Hmmm....then it's my bet that a planet without land would be a planet without ice (given our current climate at least). |
Yes, this is probably so. Icebergs and glaciers are freshwater, so you probably couldn't have freshwater chunks of ice forming in the middle of a saltwater ocean.
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| Ishmael wrote: | | Ahhh... a significant question! There is an answer. |
The source of the ice comes from underneath, not above?
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Komorikid
In: Gold Coast, Australia
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| Yes, this is probably so. Icebergs and glaciers are freshwater, so you probably couldn't have freshwater chunks of ice forming in the middle of a saltwater ocean. |
Sorry to put the kybosh on this one but the North Pole ice pack is freshwater ice floating on a salt water Arctic Sea.
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Mick Harper
Site Admin
In: London
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| If both polar ice packs were free to move the consequences would be very different. |
Which is presumably the reason Gaia didn't choose that particular arrangement.
| Experiments conducted on the west coast of Ireland found that particles were emitted into the atmosphere only during the daytime |
The first confirmation that the westward and eastward effect is derived via the sun's rays acting through a medium.
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| Komorikid wrote: | | Yes, this is probably so. Icebergs and glaciers are freshwater, so you probably couldn't have freshwater chunks of ice forming in the middle of a saltwater ocean. |
Sorry to put the kybosh on this one but the North Pole ice pack is freshwater ice floating on a salt water Arctic Sea. |
But I thought what Ishmael was saying was that the ice forms when it is touching land, and then floats out into the water.
Have they ever tried this in a lab? If you take a big tank of saltwater, and then sprinkle freshwater on it and swirl it around or whatever, and make it colder, will you get freshwater ice cubes floating in the tank?
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Komorikid
In: Gold Coast, Australia
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| Have they ever tried this in a lab? If you take a big tank of saltwater, and then sprinkle freshwater on it and swirl it around or whatever, and make it colder, will you get freshwater ice cubes floating in the tank? |
We don't need a lab; nature does it every year in the form of seasonal ice floes. It doesn't need land nearby, it just needs the temperature to be below the specific threshold for water to turn to ice.
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Mick Harper
Site Admin
In: London
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AE points out that the whole of the Earth Sciences suffer from the fact that there is only one earth and therefore it is impossible to duplicate observations. And being so big it is impossible to duplicate things in the laboratory. This means that any old theory, so long as it has the support of peer review, can hang around indefinitely, whether true or false. It is essentially non-disprovable.
For instance, one of our theories involves the hypothesis that in normal circumstances the ocean cannot evaporate -- sea level is essentially the 'evaporation point'. Orthodoxy on the other hand believes in the Hydrological Cycle and holds that the oceans cannot help but evaporate and do so all the time. How would one go about testing both propositions "in the lab"?
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Komorikid
In: Gold Coast, Australia
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| For instance, one of our theories involves the hypothesis that in normal circumstances the ocean cannot evaporate -- sea level is essentially the 'evaporation point'. Orthodoxy on the other hand believes in the Hydrological Cycle and holds that the oceans cannot help but evaporate and do so all the time. How would one go about testing both propositions "in the lab"? |
Again you don't need a lab for this one either. Pour a litre of water into a non-porous bowl (ceramic or stainless steel) and set it on your kitchen window sill or anywhere in your house for that matter. Wait a week and then see how much water is left. Depending on the ambient temperature most or all of the water will be gone. You didn't heat it up to 100°C it just disappeared. The ocean is just a bigger bowl of water.
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Ishmael
In: Toronto
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| Komorikid wrote: | | Sorry to put the kybosh on this one but the North Pole ice pack is freshwater ice floating on a salt water Arctic Sea. |
Yes. But the ice is "seeded" by the presence of land. That's my notion.
The ice forms initially on the land then grows outward. Once formed, it can extend over the salt water. But without the land it would not form - not in the ocean.
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Komorikid
In: Gold Coast, Australia
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| The ice forms initially on the land then grows outward. Once formed, it can extend over the salt water. But without the land it would not form - not in the ocean. |
This is not the case. Grease Ice and Pancake Ice form on the surface of the sea well beyond land. This is the predominant form of Pack Ice. I think you're confusing Pack Ice with Ice Shelves that do extend from land. Pack Ice forms anywhere the temperature is sufficiently low for salt water to freeze (around -2°C).
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Mick Harper
Site Admin
In: London
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| Again you don't need a lab for this one either. Pour a litre of water into a non-porous bowl (ceramic or stainless steel) and set it on your kitchen window sill or anywhere in your house for that matter. Wait a week and then see how much water is left. |
Don't you realise, Komoro, that this is precisely why the paradigm exists in the first place. 'Everybody' knows that evaporation works everywhere, all the time. AEists are supposed to go a teensy bit further. It may have escaped your notice but while scaling down you have kept one side of the equation exactly the same as before (the atmosphere) but reduced the other (the bowl of water) by about twenty-eight zillion zillion times.
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Komorikid
In: Gold Coast, Australia
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| It may have escaped your notice but while scaling down you have kept one side of the equation exactly the same as before (the atmosphere) but reduced the other (the bowl of water) by about twenty-eight zillion zillion times. |
I've just used an easily understood experiment. It works no matter the scale. If you want actual scale then do it in an enclosed bathroom. Put the water in the bath and close the door. Bath water = sea; air in the bathroom = atmosphere. You still get the same result whatever the scale. Salt water evaporates even faster.
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