Sea breeze and Chinese lantern question

  • #1

Summary:

Would a Chinese lantern launched from off shore at the mouth of a river at night travel up the river? I thought the Sea breeze blew out from land at night.
Here is what I saw one night. I was at the mouth of a river. It was early evening totally dark out. Off in the distance straight out from the mouth I saw a small orange light like a Chinese lantern. It was coming to the mouth and directly up river. When it was across from me over the middle of the river no more than 2 or 3000 feet up I would say it looked like a Chinese lantern. There was little to no wind where I was. About a half mile up the river there is a large six lane bridge crossing the river with the highway easily visible from where I was. When the lantern got to the bridge it took a right turn and followed the highway until it faded in the distance still over the highway moving slowly. It was moving about as fast as I would say a lantern would. It was traveling north on the river and east on the highway. Shortly after it disappeared another one appeared over the ocean and did the exact same thing on the exact same path.

Given what we know about the sea breeze on the shore of an ocean during the day and at night is this what a Chinese lantern would do when launched from off shore at night? I was under the impression that the sea breeze blows out from the shore at night, not in. I’m not interested in discussing what it was I’m only interested in what the wind does in this situation.
 

Answers and Replies

  • #2
PhanthomJay
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A sea breeze sets up during the day when a large body of water is cooler than the land temperature and when the prevailing winds over land are light. A very localized area of low pressure sets up and the wind blows from the water during the day towards land, generally perpendicular to the water/land interface. It usually dissipates during the late afternoon.

When the wind blows from land to water, again during otherwise light prevailing winds, it is called a land breeze, which occurs at night when the air temp over land is cooler than the water temp. But again, the breeze would be from land to water and perpendicular to the interface, and with little wind, I doubt you had a land breeze strong enough to reverse the normal flow of the river, unless normal river currents are weak.

There may be something else going on, but I’m not sure what. I live near the ocean where sea breezes are common in late spring and into summer, very localized sometimes occurring within only several hundred feet inland from the ocean, and at night it blows from land but is not a land breeze by definition, it is the prevailing wind direction from the strong high pressure area off shore which blows from over land.
 
  • #3
256bits
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  • #4
I don’t think it was visible. And this was in the summer by the way it was warm out. So are you people saying that this should’ve been moving out to sea instead of up the River? Because that’s what I thought and that’s why I made this post. What about the altitude, how high up to these Breezes work?
 
  • #5
tech99
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It might not be sea breeze as it could be the gradient wind. There is also variation of wind direction/speed with height.
 
  • #6
Tom.G
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The background circadian wind direction seems to depend on North-South hemisphere location, whether you are on an East or West coast, and the topography of the region. To a lesser extent to the presence other nearby water bodies and of Heat Islands such as large paved cities. Then of course there are the regional weather systems.

As none of the above have been stated, and there may not be many meteorologists, climatologists, or psychics here, I'm not sure your original question can be reasonably answered. If you can supply the above information, we have a better chance of making an educated, wild, guess as to what is going on.

Awaiting further details.
 
  • #7
256bits
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I don’t think it was visible. And this was in the summer by the way it was warm out. So are you people saying that this should’ve been moving out to sea instead of up the River? Because that’s what I thought and that’s why I made this post. What about the altitude, how high up to these Breezes work?
https://en.wikipedia.org/wiki/Tidal_bore


So where the moon was, can give you some indication if you were at the beginning of a high tide.
The ocean, or sea, tides can move up a river to a certain extent.
Rather than being moved by the wind, the lantern could have been following the water from the sea as it moved from sea to river mouth and farther up.

It's called a tidal bore. At some locations the bore is fairly noticeable, and at other locations not at all even though the river is moving "backwards".

https://en.wikipedia.org/wiki/Tidal_bore
 
  • #8
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First, clarifying the question. People here seem to think you are talking about a lantern floating on water. (I sense that because they discuss movement of water and tides.) It appears you refer to a lantern floating in the air. I don't know how a lantern floating on water could follow a road, as you describe, so I presume I am correct.

Assuming I am correct, I present my credentials. I am a former USAF meteorologist who forecast the weather in an area with frequent and pronounced land and sea breezes (Travis AFB, aside the Suisun Slough where land/sea breezes would accelerate, even forming a jet stream), I have ample experience being reminded that average weather conditions are products of the imagination - the average is only a statistic. The average is not an immediate reality.

Second, the relevance of my credentials is minimal! The problem here is basic. You are making assumptions that are unsupported. This is why you seem confused. So, let me break down my perception of this situation.

1. You are making an assumption , that highly simplified land/sea breeze dynamics were determining wind flow. Can you provide proof that your assumption is robust? Can you provide information about pressure gradients? What about heat flux distribution from the surface? (The idealized land/sea breeze has one rectangular surface with more heat flux than an adjacent rectangle.)

2. You also assume that your understanding of sea/land breeze dynamics is undermined by your observations if your observations don't comport with an expected land/sea breeze pattern. Well, maybe you DO have a good understanding of a simplified land/sea breeze diurnal model, but you simply have an obseravtion that is not occurring during a scenario OR EVEN A PLACE where the simplified model would apply.
For example, large bodies of water, even rivers, can act as the equivalent of the sea. Convergence/divergence can be different around a T-shaped body of water (river meeting sea). Most importantly, the wind could be affected by any number of things like a self-organized motion anomalous to the volume-average flow in the lower boundary layer or a katabatic breeze from a nearby source. You could have boundary layer separation so there is no effective land breeze at night at the surface. Things are not always what simple models predict.

The two points I make substantiate the conclusion that you don't have a strong case to say your observations contradict your understanding of the simplified land/sea breeze model.

I will add this, though. At Travis AFB, the sea/land breeze was significantly delayed relative to sunset/sunrise. Max temperature could occur in the later afternoon and max wind would not really hit until the evening. It would be dark and the sea breeze was roaring, causing wind shear challenges for even the massive C-5 aircraft landing there. They can't easily accelerate when the wind shear robs them of airspeed!

The wind delay (summer time mostly) was due to the massive diurnal pressure forcing within California's central valley. As the atmosphere heats up in the valley, pressure increases at some point due to the expansion of the air unable to keep up with the building energy! Then the atmospheric column expansion accelerates and even overshoots equilibrium as it rises upward, causing pressure to start falling after sun down. Likewise, the air column would "come back down to Earth" and compress the surface air later, going past equilibrium and causing pressure to spike in the early AM. The diurnal surface pressure evolution was far dominant over synoptic weather in the majority of days.
 

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