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#1
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I live on the western edge of Australia, with the Indian ocean 10 km
to the west, and the vast desert interior of Australia a few hundred kilometers to the east. I've been watching dew point temperature refreshed every 10 minutes on the weather bureau's website, and I'm wondering what happens to a moist sea breeze when it blows over the interior, and then returns much drier. It hasn't dropped any rain, but yet it somehow dries. If it cools below the dew point (even frost point) overnight, would it not regain that frost/dew when the land warms up? Or would there be a time lag, so you would get dried masses of air, that have not had the opportunity to recapture the dew/frost and then later masses carrying this evaporated precipitation? Does the desert act as a dessicant at all? Perhaps some of the dew/frost (is this called precipitation?) is lost to lower soil profiles? Just now, we have an easterly wind that appears to be getting increasingly humid (specific) and I'm guessing that this actual air has either not gone over much desert, or has not dropped below the dew point overnight and is merely a returnimg sea breeze with all of yesterday afternoon's ocean-derived moisture. Anyone have any opinions on this? jack |
#2
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![]() wrote in message ... I live on the western edge of Australia, with the Indian ocean 10 km to the west, and the vast desert interior of Australia a few hundred kilometers to the east. I've been watching dew point temperature refreshed every 10 minutes on the weather bureau's website, and I'm wondering what happens to a moist sea breeze when it blows over the interior, and then returns much drier. It hasn't dropped any rain, but yet it somehow dries. If it cools below the dew point (even frost point) overnight, would it not regain that frost/dew when the land warms up? Or would there be a time lag, so you would get dried masses of air, that have not had the opportunity to recapture the dew/frost and then later masses carrying this evaporated precipitation? Does the desert act as a dessicant at all? Perhaps some of the dew/frost (is this called precipitation?) is lost to lower soil profiles? Just now, we have an easterly wind that appears to be getting increasingly humid (specific) and I'm guessing that this actual air has either not gone over much desert, or has not dropped below the dew point overnight and is merely a returnimg sea breeze with all of yesterday afternoon's ocean-derived moisture. Anyone have any opinions on this? jack I would imagine you're not getting the same air back - or at least it has mixed with "continental" air that has much lower humidity. In fact, after thinking about it, it's hard to how it would not mix with other air. cheers Bill |
#3
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![]() wrote ... I live on the western edge of Australia, with the Indian ocean 10 km to the west, and the vast desert interior of Australia a few hundred kilometers to the east. I've been watching dew point temperature refreshed every 10 minutes on the weather bureau's website, and I'm wondering what happens to a moist sea breeze when it blows over the interior, and then returns much drier. It hasn't dropped any rain, but yet it somehow dries. I am not a meteorologist but I think that you are talking about surface wind. This from the ocean must be wet (near the surface). Next, above the vast desert interior, the humidity migrate up an when the aie come back the content of the water in the surface layer is lower. The migration ( and the "lost" of water) is possible for the following reason: 1. During the day the temperature is higher and a thermal emission of electrons from soil is intensive. Water droplets gain the electrons and migrate up follows the Coulomb law. Such heavy jons do not fall down easy. 2. Water molecules always migrate up because they are lighter than the molecules O2 and N2. 3. The water which migrate enough up do not come back because at wery high altitudes winds do not change the directions at night. If it cools below the dew point (even frost point) overnight, would it not regain that frost/dew when the land warms up? Or would there be a time lag, so you would get dried masses of air, that have not had the opportunity to recapture the dew/frost and then later masses carrying this evaporated precipitation? Does the desert act as a dessicant at all? Perhaps some of the dew/frost (is this called precipitation?) is lost to lower soil profiles? Just now, we have an easterly wind that appears to be getting increasingly humid (specific) But the content of water is probably lower. and I'm guessing that this actual air has either not gone over much desert, or has not dropped below the dew point overnight and is merely a returnimg sea breeze with all of yesterday afternoon's ocean-derived moisture. Anyone have any opinions on this? S* jack |
#4
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On Sun, 13 Jan 2008 14:25:29 +1100, "Landy" wrote:
wrote in message .. . I live on the western edge of Australia, with the Indian ocean 10 km to the west, and the vast desert interior of Australia a few hundred kilometers to the east. I've been watching dew point temperature refreshed every 10 minutes on the weather bureau's website, and I'm wondering what happens to a moist sea breeze when it blows over the interior, and then returns much drier. It hasn't dropped any rain, but yet it somehow dries. If it cools below the dew point (even frost point) overnight, would it not regain that frost/dew when the land warms up? Or would there be a time lag, so you would get dried masses of air, that have not had the opportunity to recapture the dew/frost and then later masses carrying this evaporated precipitation? Does the desert act as a dessicant at all? Perhaps some of the dew/frost (is this called precipitation?) is lost to lower soil profiles? Just now, we have an easterly wind that appears to be getting increasingly humid (specific) and I'm guessing that this actual air has either not gone over much desert, or has not dropped below the dew point overnight and is merely a returnimg sea breeze with all of yesterday afternoon's ocean-derived moisture. Anyone have any opinions on this? jack I would imagine you're not getting the same air back - or at least it has mixed with "continental" air that has much lower humidity. In fact, after thinking about it, it's hard to how it would not mix with other air. cheers Bill Thanks Bill, I agree, but my question was more to a simple easterly gale overnight and morning (and we have thousands of miles of desert out there) and a sea breeze (gale) in the afternoon. No rain has occurred, but the desert wind is much much drier than the sea breeze. Or are you saying that the reason that winds off the desert are dry is because they MUST have dropped their moisture as precipitation somewhere? I'm just asking the question whether deserts can have some drying effect by way of being a dessicant or some other non-rain moisture loss. jack |
#5
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On Sun, 13 Jan 2008 11:28:51 +0100, "Szczepan Bialek"
wrote: wrote .. . I live on the western edge of Australia, with the Indian ocean 10 km to the west, and the vast desert interior of Australia a few hundred kilometers to the east. I've been watching dew point temperature refreshed every 10 minutes on the weather bureau's website, and I'm wondering what happens to a moist sea breeze when it blows over the interior, and then returns much drier. It hasn't dropped any rain, but yet it somehow dries. I am not a meteorologist but I think that you are talking about surface wind. This from the ocean must be wet (near the surface). Next, above the vast desert interior, the humidity migrate up an when the aie come back the content of the water in the surface layer is lower. The migration ( and the "lost" of water) is possible for the following reason: 1. During the day the temperature is higher and a thermal emission of electrons from soil is intensive. Water droplets gain the electrons and migrate up follows the Coulomb law. Such heavy jons do not fall down easy. 2. Water molecules always migrate up because they are lighter than the molecules O2 and N2. 3. The water which migrate enough up do not come back because at wery high altitudes winds do not change the directions at night. Ahh, thanks so much for that, Szczepan, I'd not even considered the air column behaving very differently at different altitudes. Of course, the sea breeze loses its moisture out in the desert mainly coz it (the moisture) moves upward and I at 6' tall only "see" the air at my altitude. And here was I trying to engineer a way for the moisture to go the other way down to the great artesian basins ![]() I was not aware of this thermal emission of electrons out in the desert, and what water droplets would be present at such usually low relative humidities? If it cools below the dew point (even frost point) overnight, would it not regain that frost/dew when the land warms up? Or would there be a time lag, so you would get dried masses of air, that have not had the opportunity to recapture the dew/frost and then later masses carrying this evaporated precipitation? Does the desert act as a dessicant at all? Perhaps some of the dew/frost (is this called precipitation?) is lost to lower soil profiles? Just now, we have an easterly wind that appears to be getting increasingly humid (specific) But the content of water is probably lower. No it's getting higher, (g/kg), I'm not talking relative humidity here. But at the moment, the air passing my city is unusually moist. I suspect it is not spending much time away from the sea with the present patterns. and I'm guessing that this actual air has either not gone over much desert, or has not dropped below the dew point overnight and is merely a returnimg sea breeze with all of Anyone have any opinions on this? jack |
#6
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![]() Uzytkownik napisal w wiadomosci ... On Sun, 13 Jan 2008 11:28:51 +0100, "Szczepan Bialek" wrote: . And here was I trying to engineer a way for the moisture to go the other way down to the great artesian basins ![]() Probably some percent of water migrate down (in the soil) and some up. I was not aware of this thermal emission of electrons out in the desert, and what water droplets would be present at such usually low relative humidities? It is known that air which is not dry discharge charged bodies. Electrons and water molecules make an aggregates (we can say droplets). In the Earth electric field one electron can lift 10^8 water molecules. UV radiation and high temperature do the work. If it cools below the dew point (even frost point) overnight, would it not regain that frost/dew when the land warms up? Or would there be a time lag, so you would get dried masses of air, that have not had the opportunity to recapture the dew/frost and then later masses carrying this evaporated precipitation? Does the desert act as a dessicant at all? Perhaps some of the dew/frost (is this called precipitation?) is lost to lower soil profiles? Just now, we have an easterly wind that appears to be getting increasingly humid (specific) But the content of water is probably lower. No it's getting higher, (g/kg), I'm not talking relative humidity here. But at the moment, the air passing my city is unusually moist. I suspect it is not spending much time away from the sea with the present patterns. It is possible if no electrons and when "the air is not spending much time away from the sea ". But I am not an expert. and I'm guessing that this actual air has either not gone over much desert, or has not dropped below the dew point overnight and is merely a returnimg sea breeze with all of The wind speed can have something to do also. S* |
#7
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#8
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![]() wrote in message ... On Sun, 13 Jan 2008 14:25:29 +1100, "Landy" wrote: wrote in message . .. I live on the western edge of Australia, with the Indian ocean 10 km to the west, and the vast desert interior of Australia a few hundred kilometers to the east. I've been watching dew point temperature refreshed every 10 minutes on the weather bureau's website, and I'm wondering what happens to a moist sea breeze when it blows over the interior, and then returns much drier. It hasn't dropped any rain, but yet it somehow dries. If it cools below the dew point (even frost point) overnight, would it not regain that frost/dew when the land warms up? Or would there be a time lag, so you would get dried masses of air, that have not had the opportunity to recapture the dew/frost and then later masses carrying this evaporated precipitation? Does the desert act as a dessicant at all? Perhaps some of the dew/frost (is this called precipitation?) is lost to lower soil profiles? Just now, we have an easterly wind that appears to be getting increasingly humid (specific) and I'm guessing that this actual air has either not gone over much desert, or has not dropped below the dew point overnight and is merely a returnimg sea breeze with all of yesterday afternoon's ocean-derived moisture. Anyone have any opinions on this? jack I would imagine you're not getting the same air back - or at least it has mixed with "continental" air that has much lower humidity. In fact, after thinking about it, it's hard to how it would not mix with other air. cheers Bill Thanks Bill, I agree, but my question was more to a simple easterly gale overnight and morning (and we have thousands of miles of desert out there) and a sea breeze (gale) in the afternoon. No rain has occurred, but the desert wind is much much drier than the sea breeze. Or are you saying that the reason that winds off the desert are dry is because they MUST have dropped their moisture as precipitation somewhere? I'm just asking the question whether deserts can have some drying effect by way of being a dessicant or some other non-rain moisture loss. jack Jack, No - I'm just saying that because the high-humidity air that blew in from the sea mixed with very low-humidity air in the desert, the resulting humidity of the mixed air that blows back out will be lower. It's a matter of mixing ratios. I guess the absolute moisture loss (of the air that blows back) has been to the desert air - it doesn't have to have precipitated. I think if you did humidty measurements inland in the deserts on evenings following the sea breezes versus days without, you would see the difference. I hope this makes sense. cheers Bill |
#9
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![]() "Landy" wrote ... wrote I'm just asking the question whether deserts can have some drying effect by way of being a dessicant or some other non-rain moisture loss. jack Jack, No - I'm just saying that because the high-humidity air that blew in from the sea mixed with very low-humidity air in the desert, the resulting humidity of the mixed air that blows back out will be lower. It's a matter of mixing ratios. I guess the absolute moisture loss (of the air that blows back) has been to the desert air - it doesn't have to have precipitated. I think if you did humidty measurements inland in the deserts on evenings following the sea breezes versus days without, you would see the difference. I hope this makes sense. "At high altitudes, the difference between between high pressures from warm tropical air and low pressures from cold polar air try to force air from the tropics toward the poles, but the Earth's rotation diverts this flow to the east, resulting in the high velocity west-to-east jet stream flows at mid-latitudes." It is from: http://aes.gsfc.nasa.gov/vis/a000000/a003200/a003203/ Jack lives on the western edge of Australia. So the water which migrate very high above the desert flows to the east and we have "absolute moisture loss". But what things are on the eastern edge of Australia? S* |
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