Why the afternoon Sun is the hottest? (scan, comparison, power)
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So that tells you there are more things at work than just the sun angle.
Well yes of course. The amount of energy we received from the sun at any given point of the day need not coincide with the hottest part of the day. We still don't really know which one the OP meant. The sun can certainly be providing more energy at times of the day when it's not the hottest ambient temp. Perhaps not drastically different times, but still.
Have you heard of heat (or cooling) effects from convection ? As the earth rotate, the atmosphere creates a shear layer effects called "wind". The wind mixes cooler part of atmosphere with heated air by the sun more effectively & faster than others mode of transferring heat/ cold.
Also for those of you who argue that the mid-day sun is strongest as it's "directly overhead", implying it's because the shortest distance between the sun and the ground, whereas the afternoon sun's intensity much of it is absorbed by more air. It's a geometry thing, I get what you're saying.
But if that's true then, according to your theory the distance furtherest from the sun should be cooler, for example, places that is below the sea level (such as the Death Valley) vs. places that's closest to the sun, such as the peak of Mt. Whitney. We all know that's not true.
It's not about distance from the sun being closer or not as close. The minute difference in distance due to elevation or rotation is insignificant. But it does have a lot to do with the amount of atmosphere protecting you (as well as what the local constituents are such as water vapor content). Elevation can make a difference in the amount of atmosphere protecting you. In morning or evening, the sun is close to the horizon and the light has to come through hundreds of miles of atmosphere to reach you. In the middle of the day, directly overhead, there's only a few miles of any significant protection. Likewise a very dry climate, the desert for example, has little water vapor to provide any protection. For an easy to see example, a cloudy day vs a clear day.
Granted there is a lot of other effects going on as well, but this is a simplification.
The sun doesn't become hotter during the afternoon. The temperature of the sun doesn't vary significantly around the clock.
But as the day progresses from morning to afternoon, more humidity tends to be burned off (which is normally a cushioning and moderating factor), and the height of the sun puts more radiation down on us through less layers of the atmosphere (rather than through more layers of the atmosphere when low in the sky).
As a pale Caucasian, I can tell you that while the ambient temperature is highest at 4:00PM-5:00PM, it takes less time to get sunburned at Noon than at 4:00PM-5:00PM.
It's not. The surface temperature of the sun is around 5770K. It's not like it knows when it's the afternoon for you and turns the temperature up.
If you want to know when sunlight is the most intense, it's whenever it's at 90 degrees. That just has to do with angle of incidence. The more sunlight is coming in at an angle (in the morning and afternoon), the more it gets refracted in the atmosphere. Zenith or solar noon is when the sunlight is the "hottest". But it's not really any different than say your stove. The flame (if gas) is producing the most heat when the dial is all the way open at 10 or whatever it is for your stove. If you then turn dial down on the stove from 10 to 6, if the water was 80 degrees it's still going to continue to get hotter after you turn the dial down. The water is still getting hotter even though the amount of heat from the stove is less at "6" than "10". Eventually if you have a very, very large pot and keep turning the dial down, though, the water in the pot is going to start to cool off. Surface temperature on the earth typically reaches its highest around 4 hours after solar noon. It's a really big pot of water and since the sun is very far away it's relatively a very weak stove in comparison to sauce pan of water and kitchen stove analogy.
It's not. The surface temperature of the sun is around 5770K. It's not like it knows when it's the afternoon for you and turns the temperature up.
If you want to know when sunlight is the most intense, it's whenever it's at 90 degrees. That just has to do with angle of incidence. The more sunlight is coming in at an angle (in the morning and afternoon), the more it gets refracted in the atmosphere. Zenith or solar noon is when the sunlight is the "hottest". But it's not really any different than say your stove. The flame (if gas) is producing the most heat when the dial is all the way open at 10 or whatever it is for your stove. If you then turn dial down on the stove from 10 to 6, if the water was 80 degrees it's still going to continue to get hotter after you turn the dial down. The water is still getting hotter even though the amount of heat from the stove is less at "6" than "10". Eventually if you have a very, very large pot and keep turning the dial down, though, the water in the pot is going to start to cool off. Surface temperature on the earth typically reaches its highest around 4 hours after solar noon. It's a really big pot of water and since the sun is very far away it's relatively a very weak stove in comparison to sauce pan of water and kitchen stove analogy.
Excellent explanation.
The OP said he had a theory, I wish he would post it.
It's not. The surface temperature of the sun is around 5770K. It's not like it knows when it's the afternoon for you and turns the temperature up.
If you want to know when sunlight is the most intense, it's whenever it's at 90 degrees. That just has to do with angle of incidence. The more sunlight is coming in at an angle (in the morning and afternoon), the more it gets refracted in the atmosphere. Zenith or solar noon is when the sunlight is the "hottest". But it's not really any different than say your stove. The flame (if gas) is producing the most heat when the dial is all the way open at 10 or whatever it is for your stove. If you then turn dial down on the stove from 10 to 6, if the water was 80 degrees it's still going to continue to get hotter after you turn the dial down. The water is still getting hotter even though the amount of heat from the stove is less at "6" than "10". Eventually if you have a very, very large pot and keep turning the dial down, though, the water in the pot is going to start to cool off. Surface temperature on the earth typically reaches its highest around 4 hours after solar noon. It's a really big pot of water and since the sun is very far away it's relatively a very weak stove in comparison to sauce pan of water and kitchen stove analogy.
Not bad, but let me pose a counter-argument.
The distance between the Earth and the Sun is 94.465 million miles. The heat from the sun was transmitted via radiation. Do you really think the distance from the Sun between Noon and 5pm is going to make a difference on the rate in which Sun's heat is radiated to the ground?
Back to the gardening argument, the garden experts recommend "shade clothes" for plants for "harsh & harmful" Sun in the afternoon, not the heat built up during the day. So clearly this is the issue of Sun intensity as opposed to the cumulative heat built up during the day.
In my experience, the sun is not hotter in the afternoon, it's just that the temperature is hotter then. Here, the temperature on a sunny day peaks about 5pm, when it's actually going down behind the big trees to the west of us. What I noticed one day was that in my front yard which is mostly lawn, it was comfortably hot. When I went to the store less than a mile away, and got out of the car, it was almost unbearably hot. Thinking about it, I formed my theory, it's the buildup of heat on the ground, especially concrete during the day. By afternoon, you have the sun still providing heat, but in addition, the heat coming up from the ground.
I am also east of Seattle and my experience mirrors yours.
The distance between the Earth and the Sun is 94.465 million miles. The heat from the sun was transmitted via radiation. Do you really think the distance from the Sun between Noon and 5pm is going to make a difference on the rate in which Sun's heat is radiated to the ground?
Back to the gardening argument, the garden experts recommend "shade clothes" for plants for "harsh & harmful" Sun in the afternoon, not the heat built up during the day. So clearly this is the issue of Sun intensity as opposed to the cumulative heat built up during the day.
I'm not sure that statement alone qualifies as whatever you're trying to claim. Plants benefit from cooler morning temps and, often, filtered sunlight. As the day heats up--and along with it the soil, plants themselves, pots, etc, the heat sink plus the continued sunlight stresses some plants.
I have a nearby official weather station I check (online) every day and the solar radiation (in W/sq meter) always peaks earlier than the highest temp of the day, unless there is a significant change like a cloud front rolling in.
Yesterday: highest solar power: between 12 noon and 12:15pm (the station reports every 15min), highest temp between 2 and 2:15pm
Day before: highest solar power: between 11:45am and noon, highest temp between 2:45 and 3pm
Day before that the difference was only 1.25 hours.
And so on.
==
What exactly is your theory (that isn't just based on some gardener's blog)?
It's not. The surface temperature of the sun is around 5770K. It's not like it knows when it's the afternoon for you and turns the temperature up.
If you want to know when sunlight is the most intense, it's whenever it's at 90 degrees. That just has to do with angle of incidence. The more sunlight is coming in at an angle (in the morning and afternoon), the more it gets refracted in the atmosphere. Zenith or solar noon is when the sunlight is the "hottest". But it's not really any different than say your stove. The flame (if gas) is producing the most heat when the dial is all the way open at 10 or whatever it is for your stove. If you then turn dial down on the stove from 10 to 6, if the water was 80 degrees it's still going to continue to get hotter after you turn the dial down. The water is still getting hotter even though the amount of heat from the stove is less at "6" than "10". Eventually if you have a very, very large pot and keep turning the dial down, though, the water in the pot is going to start to cool off. Surface temperature on the earth typically reaches its highest around 4 hours after solar noon. It's a really big pot of water and since the sun is very far away it's relatively a very weak stove in comparison to sauce pan of water and kitchen stove analogy.
Quote:
Originally Posted by BigfishTim
Not bad, but let me pose a counter-argument.
The distance between the Earth and the Sun is 94.465 million miles. The heat from the sun was transmitted via radiation. Do you really think the distance from the Sun between Noon and 5pm is going to make a difference on the rate in which Sun's heat is radiated to the ground?
Back to the gardening argument, the garden experts recommend "shade clothes" for plants for "harsh & harmful" Sun in the afternoon, not the heat built up during the day. So clearly this is the issue of Sun intensity as opposed to the cumulative heat built up during the day.
Not sure where you got "distance" from. Several of us, including Malloric whom you were responding to, discussed angle and the amount of atmosphere, not distance.
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