# Why does the equator stay warm all year?

#### Supreme Logic

##### New Member
Why does the equator "hot temperature ring", stay in the center rather than wobble with the seasons and tilt?

I saw this example in a Flat Earth video and am having trouble finding an answer.
Every source, even the official ones, seem to give an example of a perpendicular Earth. The ones that do address the tilt, simply say that the tilt doesnt have any effect of the temperature.... does anyone have the long answer?

NOAA video for reference:

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You can clearly see the warm band moving up and down in that video. The temperature in the tropics is fairly even.

I really don't see the problem here, perhaps you could explain more.

If you mean the orange band seen on the equator in the pacific, and to a lesser extent the (but not the indian ocean),

that is cooler water introduced by the south pacific gyre. Those currents stay the same year round relative to the equator, which gives you that orange/yellow line on the animation. But the larger (and warmer) red/orange band is moving as expected.

I suppose I expected more of an axis tilt/wobble rather than "bobbing", considering its a video of the entire Earth

I suppose I expected more of an axis tilt/wobble rather than "bobbing", considering its a video of the entire Earth

Hmm, I kind of see your confusion there, but the video is 100% correct. I'd suggest watching some videos illustrating the seasons, like this one. Watch it in full, and at each stage imagine how heat distribution looks on a globe and one the map.

Hmm, I kind of see your confusion there, but the video is 100% correct. I'd suggest watching some videos illustrating the seasons, like this one. Watch it in full, and at each stage imagine how heat distribution looks on a globe and one the map.

Your video shows that there is about 47 degrees of wobble per year in relation to the suns rays, right?

What it the actual reason for warm temperatures on the equator? ive found mixed answers on many official sources

Your video shows that there is about 47 degrees of wobble per year in relation to the suns rays, right?

There's no real wobble affecting the temperature in that video. The axis of the earth is tilted 23.5°, but that tilt does not change much - it's just on one side of the sun or the other, so tilting towards or away from the sun, so the range is +23.5 to -23.5

What it the actual reason for warm temperatures on the equator? ive found mixed answers on many official sources

The higher overhead the sun is, the more sun there is per surface area, and the less atmosphere the sun has to go through, so it's hotter. It's explained in the video.

It's important to realized that the Earth's axis does not move significantly over the years, it stays pointing in the same direction. The Earth moves around the sun, and that's what causes the seasons - the position of the tilt relative to the sun.

I'm posting a comment here because the issue raised seemed closest to this thread.

I was just watching the new Netflix series Our Planet II when I noticed it gave an explanation of the changing seasons which may perpetuate the common misconception that the earth's axis of rotation 'tilts' or 'swings' during the course of the year. The dubious explanation comes around minute 10 of Episode 1. The commentary is narrated by David Attenborough, but I couldn't find out whether he wrote the text.

The text is at best ambiguous. It does use the word 'swings' in describing the changing inclination of the axis towards the north pole of the earth. Many viewers are likely to interpret this as meaning that the direction of the axis moves in relation to the plane of the earth's orbit, which is the common misconception. Charitably, one might think that the writer has just made a poor choice of words. But it is more difficult to be charitable about the accompanying animation, where a line is drawn through the poles to show the direction of the axis as the earth completes an orbit.. To my eyes, at least, it seems unambiguously to change its inclination to the orbital plane. (See especially around 10:40) But my eyes may be deceiving me, and I would be interested to know whether other people with access to the documentary share my impression. Since the animated view is presented from an unspecified point in empty space, it is conceivable that the shifting of the axis could be explained by a shifting viewpoint, but this in itself would be a poor decision by the animation team.

The higher overhead the sun is, the more sun there is per surface area, and the less atmosphere the sun has to go through, so it's hotter. It's explained in the video.
To add on to this, the less atmosphere for the sun's photons to go through, the less scattering they experience. Less scattering means those photons reach Earth. More scattering means the photons may be scattered back into space. Scattering is minimized when the photons angle of incidence is 90 degrees, i.e. straight at the Earth like we have at the equator.

To add on to this, the less atmosphere for the sun's photons to go through, the less scattering they experience. Less scattering means those photons reach Earth. More scattering means the photons may be scattered back into space. Scattering is minimized when the photons angle of incidence is 90 degrees, i.e. straight at the Earth like we have at the equator.
I've never heard that this plays a major role. Can you quantify this effect?

Weather patterns (clouds!) seem far more important:
Article:
This diagram shows the percentage of sunlight that is reflected by different Earth surfaces or clouds.

I was just watching the new Netflix series Our Planet II when I noticed it gave an explanation of the changing seasons which may perpetuate the common misconception that the earth's axis of rotation 'tilts' or 'swings' during the course of the year. The dubious explanation comes around minute 10 of Episode 1.
... the seasons. And they, in turn, are a consequence of another journey: our planet's year-long loop around the sun. As it travels, it does so on a tilt of twenty-three and a half degrees, and it is this that creates our seasons. To understand how, keep your eye on the North Pole. For half the year, it is angled away from the sun, bringing darkness and winter. For the other half, it swings towards the sun, bringing longer days. It's this annual cycle that drives the greatest movements of life on Earth. And in the northern hemisphere, this brings the year's biggest change: spring. In late March, the days lengthen faster than at any other time. Sunlight increases, ...
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The part I bolded says unambiguously that the tilt is constant.
But it is more difficult to be charitable about the accompanying animation, where a line is drawn through the poles to show the direction of the axis as the earth completes an orbit.. To my eyes, at least, it seems unambiguously to change its inclination to the orbital plane. (See especially around 10:40) But my eyes may be deceiving me, and I would be interested to know whether other people with access to the documentary share my impression. Since the animated view is presented from an unspecified point in empty space, it is conceivable that the shifting of the axis could be explained by a shifting viewpoint, but this in itself would be a poor decision by the animation team.
The camera is dynamic, moving around the scene, and the apparent shifting of the axis is definitely due to the shifting viewpoint.

I take more issue with the fact that Earth is not rotating in the animation, but appears tidally locked to the sun. And the audio effects are using the "space whoosh".

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I've never heard that this plays a major role. Can you quantify this effect?

Weather patterns (clouds!) seem far more important:
Article:
This diagram shows the percentage of sunlight that is reflected by different Earth surfaces or clouds.
In addition, the total solar irradiance is the maximum power the Sun can deliver to a surface that is perpendicular to the path of incoming light. Because the Earth is a sphere, only areas near the equator at midday come close to being perpendicular to the path of incoming light. Everywhere else, the light comes in at an angle. The progressive decrease in the angle of solar illumination with increasing latitude reduces the average solar irradiance by an additional one-half.

Please don't use quote tags for external content, it gets lost when replying, and I have to copy it back in by hand. Use EX tags:

In addition, the total solar irradiance is the maximum power the Sun can deliver to a surface that is perpendicular to the path of incoming light. Because the Earth is a sphere, only areas near the equator at midday come close to being perpendicular to the path of incoming light. Everywhere else, the light comes in at an angle. The progressive decrease in the angle of solar illumination with increasing latitude reduces the average solar irradiance by an additional one-half.
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This quote is about the tilt of the surface, about it being perpendicular or at an angle. I was asking about your claim regarding atmospheric scattering. These are two different aspects.

The part I bolded says unambiguously that the tilt is constant.
No, it just says that there is a tilt of twenty-three and a half degrees. That would not exclude the axis 'swinging' round in a circle, provided it always maintains the same angle of inclination to the orbital plane. And that is probably how some people would interpret the later phrase 'it swings towards the sun'. It is a paradigm case of ambiguity! To remove the ambiguity, the text would need to describe the tilt as 'constant', 'unchanging', 'fixed' or some such phrase, and emphasise that it is the orbital movement of the earth as a whole which is responsible for the changing amount of exposure to the sun. This is clearly and concisely explained in Mick's #8 above. It's a pity he wasn't hired as scriptwriter!

That would not exclude the axis 'swinging' round in a circle, provided it always maintains the same angle of inclination to the orbital plane.
Relative to the line Sun-Earth, it does. If you see the Sun-Earth line as swinging round, it doesn't.
It's a minor simplification.
(Anything is better than people thinking it's to do with Earth's elliptical orbit.)

P.S. "Many viewers are likely to interpret this as meaning that the direction of the axis moves in relation to the plane of the earth's orbit, which is the common misconception." If you have no other reference point than this plane, you can't detect motion if the angle of inclination stays the same: geometrically, in that plane, Sun could be moving around Earth. Thus, "the direction of the axis moves in relation to the plane" must be interpreted to mean that the angle changes—but these are your words! You should've said, "the axis of the Earth moves in yearly cycles relative to the celestial background" or maybe referenced inertial space (if that is a thing).

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If you have no other reference point than this plane, you can't detect motion if the angle of inclination stays the same:
I think we must be using 'angle of inclination' in different senses. If you are standing on a flat floor, and give a Nazi salute at 45 degrees to the floor, towards the east, then pivot on your heels until you are saluting towards the west, while maintaining the angle of 45 degrees throughout, I would say that the angle of inclination of your arm relative to the floor remains the same, but motion can easily be detected, because your hand will be pointing to quite different objects at the beginning and end of the exercise (and at times in between). In the case of the earth, if its axis of rotation 'swung round' during its orbit, while maintaining an angle of 23.5 degrees relative to the orbital plane (which is how I described it), its motion could be detected because it would be pointing towards different stars at different times. Indeed, over the long term there is a slight change of this kind due to nutation. The 'common misconception' that I keep referring to is the idea that the cycle of the seasons is due to an annual change of this kind.

Perhaps I am wrong in thinking that this is a common misconception, but it is not unknown. The reference to 'axis tilt/wobble' in #4 above could be an example. Some of the earth's motions could fairly be described as 'wobbles', but the seasonal cycle is not one of them.

[Apologies if anyone is triggered by references to Nazi salutes.]

Because the Earth is a sphere, only areas near the equator at midday come close to being perpendicular to the path of incoming light.
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Really badly worded, IMHO. The fuzziness of "near" and "close" don't jibe well with the precision of "at", and "near the equator at midday" conjours up images of bits of the surface of the planet moving around each morning and jostling with each other for that prime equatorial position when the clock strikes twelve (i.e. that their nearness to the equator is something that can change over time, sorry if the fantastic imagery didn't work).

its motion could be detected because it would be pointing towards different stars at different times.
that's what I said you should've written in the first place ("celestial background"), so we agree there.

mathematically, a plane doesn't have a direction, and you can define it simply via its normal (i.e. you define which way is up) and a point. The orbital plane would thus be defined by the rotation axis of the orbit (or any parallel thereof), and e.g. the sun or the earth. This works out the same no matter whether you think Earth orbits the sun, sun orbits the Earth, or any other point (e.g. their barycenter).

Really badly worded, IMHO. The fuzziness of "near" and "close" don't jibe well with the precision of "at", and "near the equator at midday" conjours up images of bits of the surface of the planet moving around each morning and jostling with each other for that prime equatorial position when the clock strikes twelve (i.e. that their nearness to the equator is something that can change over time, sorry if the fantastic imagery didn't work).
"near the equator in the morning" means the incident angle of the sunlight is small, and the irradiation measured in W/m² is small. Both conditions (near the equator/at midday) have to be approximately satisfied for the irradiation to approach the possible maximum.
It's clear when you view the quote in context.
(And it's definitely not about atmospheric scattering.)

This quote is about the tilt of the surface, about it being perpendicular or at an angle. I was asking about your claim regarding atmospheric scattering. These are two different aspects.
Perhaps I am not understanding your question. Scattering is a function of the angle of incidence (among other parameters).

We are talking about how seasons occur.
To add on to this, the less atmosphere for the sun's photons to go through, the less scattering they experience. Less scattering means those photons reach Earth. More scattering means the photons may be scattered back into space. Scattering is minimized when the photons angle of incidence is 90 degrees, i.e. straight at the Earth like we have at the equator.
You are saying that atmospheric scattering keeps photons from reaching Earth's surface.
Perhaps I am not understanding your question. Scattering is a function of the angle of incidence (among other parameters).
I've never heard that this [atmospheric scattering] plays a major role [in causing the seasons on Earth]. Can you quantify this effect? [i.e. how much of the solar energy is affected?]

Can you quantify this effect? [i.e. how much of the solar energy is affected?]
From the quote I posted above (btw thank you for showing me the correct button to use in the future): The progressive decrease in the angle of solar illumination with increasing latitude reduces the average solar irradiance by an additional one-half.

Solar irradiance is the power per unit area received from the Sun (quoting from wikipedia).

There are different types of scattering, described here. You can track down the equations as well, for example, Rayleigh Scattering on Wikipedia. This particular type of scattering is a function of the scattering angle in the form 1 + cos^2(theta).

Mick's video above describes how the angle of sunlight affects the seasons as well.

I've never heard that this [atmospheric scattering] plays a major role [in causing the seasons on Earth]. Can you quantify this effect? [i.e. how much of the solar energy is affected?]
From Wikipedia:

Average annual solar radiation arriving at the top of the Earth's atmosphere is roughly 1361 W/m2.[34] The Sun's rays are attenuated as they pass through the atmosphere, leaving maximum normal surface irradiance at approximately 1000 W/m2 at sea level on a clear day. When 1361 W/m2is arriving above the atmosphere (when the sun is at the zenith in a cloudless sky), direct sun is about 1050 W/m2, and global radiation on a horizontal surface at ground level is about 1120 W/m2.[35] The latter figure includes radiation scattered or remitted by the atmosphere and surroundings. The actual figure varies with the Sun's angle and atmospheric circumstances. Ignoring clouds, the daily average insolation for the Earth is approximately 6 kWh/m2 = 21.6 MJ/m2.

The output of, for example, a photovoltaic panel, partly depends on the angle of the sun relative to the panel. One Sun is a unit of power flux, not a standard value for actual insolation. Sometimes this unit is referred to as a Sol, not to be confused with a sol, meaning one solar day.

At a lower angle, the light must also travel through more atmosphere. This attenuates it (by absorption and scattering) further reducing insolation at the surface.

Attenuation is governed by the Beer-Lambert Law, namely that the transmittance or fraction of insolation reaching the surface decreases exponentially in the optical depth or absorbance (the two notions differing only by a constant factor of ln(10) = 2.303) of the path of insolation through the atmosphere. For any given short length of the path, the optical depth is proportional to the number of absorbers and scatterers along that length, typically increasing with decreasing altitude. The optical depth of the whole path is then the integral (sum) of those optical depths along the path.

When the density of absorbers is layered, that is, depends much more on vertical than horizontal position in the atmosphere, to a good approximation the optical depth is inversely proportional to the projection effect, that is, to the cosine of the zenith angle. Since transmittance decreases exponentially with increasing optical depth, as the sun approaches the horizon there comes a point when absorption dominates projection for the rest of the day. With a relatively high level of absorbers this can be a considerable portion of the late afternoon, and likewise of the early morning. Conversely, in the (hypothetical) total absence of absorption, the optical depth remains zero at all altitudes of the sun, that is, transmittance remains 1, and so only the projection effect applies.
[36]
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It sounds as if it's normally figured in as part of the calculation, not quoted separately, but I'll admit that I skimmed pages of mathematical calculations.

It sounds as if it's normally figured in as part of the calculation, not quoted separately
Yes. Absorption is usually named, i.e. the sun heating the atmosphere.

I finally found a figure for reflection by the atmosphere:
Article:

Atmospheric reflection affects less than 6% of the incoming solar energy, and is therefore a very minor factor in the seasonal variation of irradiance.

Yes. Absorption is usually named, i.e. the sun heating the atmosphere.

I finally found a figure for reflection by the atmosphere:
Article:

Atmospheric reflection affects less than 6% of the incoming solar energy, and is therefore a very minor factor in the seasonal variation of irradiance.
Lol I'm not sure why you disliked my response giving you the qualification you asked for. Are you denying that scattering due to the angle of incidence doesn't play a part? Is NASA not an acceptable source here? I could also upload a really bad Ms paint job to researchgate if you prefer