why is the Sun hotter in Summer than Winter ?

Question

I am puzzled - I have seen other answers to this question which say that it is the 'tilt', and I see that there is less energy reaching the northern hemisphere in Winter in total because of the angles. My question though is not about why Summer is hotter than Winter, it is about how hot the Sun feels. When the Sun is in the sky in Summer it feels hot (and burns !), whilst in Winter it does not feel so hot (even though the Sun can be at the same angle in the sky, say 10am in Summer the Sun is at the same height in the sky as at 12 o'clock in Winter). It can't just be the ambient air temperature - I can see that in Winter the air would be colder overall - the question is about radiant heat from the Sun directly; the Sun seems to be colder in Winter. I don't know why - it's the same distance away, it's at the same angle in the sky (though at different times of day).... what's the answer ?

Don't say that the Earth is nearer to the Sun in Summer 'cos it's not true !!

not sure it's 'tilt' now either - if I stand in a field (say) and we imagine the Sun is at 45 degrees to the horizon then the 'tilt' relative to me is the same, whether or not it's Winter (midday) or Summer (mid-morning) - but the Summer Sun is/feels hotter (and yes, I'm wearing more clothes in Winter - but that's not it either !!). Mustn't confuse tilt causing total energy over 24 hours to be less in Winter in the N hemisphere.... which is correct of course.

thanks all, some good answers, but all incorrect I think so far. Anyone who says 'tilt' is wrong - that does indeed cause seasons and long Summer days and leads to the fact that the Sun is higher at midday in Summer in the northern hemisphere (and the higher it goes it's 'footprint' on the surface becomes smaller, as so many people have said in different ways).

But if I can see the Sun at say 20 degrees above the horizon then it is 'point-to-point' (ie. direct from the Sun to me) and tilt does not come into it - a 20 degree angle to a point on a sphere is a constant (I could lean forwards or backwards to produce 'tilt' ! The only thing tilt does is to affect the Time of Day that the 20 degree angle occurs - it just occurs earlier in the Summer).

So, I am still asking, "For the Same Angle in the sky - important that - why is the Sun hotter in Summer than in Winter ?"

Well, I've learned one thing which I didn't expect: people only see (and answer) the question they want to see !! I love it. I know the Sun (or torch or whatever) gets higher overhead in the Summer - but that is not the question being asked. Can anyone help ??

Answer 1

Because the sun is closer to the earth in the summer.

OK I just got corrected and I guess this is the reason but I'm suprised he didn't answer the question and had to email it to me:

From: Super something

Subject: hi

Message: Hey there, the reason people gave you thumbs down on that question about summer/winter is because the sun ISNT closest to the sun in summer - its closest round about January! Its just that in the western hemisphere we're a bit prejudiced. The earth is closest to the sun in june. It's just the tilt of the earth that makes it warmer when we're in that part of the orbit where we're closer.

Answer 2

wow. I can't believe how many people believe it's because the sun earth is on an ellipse.

First, if that were the case, how do you explain it's summer right now in the southern hemisphere

Second, yes it is elliptical, but the variation is less than 0.01% and it happens that we are actually close to the sun during the northern hemisphere winter.

Ok, now to answer the main question, there are several reasons. Like you said, there is the angle at which you receive the light; it reduces the power density of the light and that means less heat. Also, the sun light has to go through more air in the atmosphere because of the angle too. Finally, you're usually wearing clothes and a jacket in the winter. That's the main reason why you don't feel the sun as much. They absorb the light to heat up but they lose it right away to the cold ambiant air. It barely has the time to actually heat up.

Oh, btw, if it's the same angle at 10 in the winter and 12 in the summer, you must not live very high up in the north :-P

Answer 3

First, in the northern hemisphere's winter, the earth is actually closer to the sun - perhelion - than it is during the summer - aphelion. Anyone who gets this mixed up needs to go back and take 7th grade science over again.

Second, the amount of heat you feel IS directly related to the tilt of the earth's axis relative to the sun, which affects the angle at which the sun's rays strike any given point on earth. In the summer, the sun's rays strike the earth more directly in the north, which means the energy reaching the surface is more "concentrated". In the winter, this angle is greater, so the same amount of energy is spread out over a greater area, causing less heat to reach the same place.

Third, the height of the sun in the sky has absolutely nothing to do with the amount of heat you feel - again, it's the angle at which the light strikes the earth.

Fourth, in the wintertime the hours of daylight are fewer due, again, to the tilt of the earth's axis. This gives the sun less time to warm a particular area, and much more time for that heat to radiate back out into space with the greater number of dark hours. In the summer, at the solstice, there are almost 18 hours of daylight in some places, which allows more heating to occur and less time for the heat to radiate before the sun returns to the same area to warm it again. In the winter there can be as few as six hours of sunlight, leaving very little time for warmth to reach the ground and a lot of time for that heat to radiate away.


To the asker: How can you know we're all wrong when you don't know the correct answer yourself?

Answer 4

The answer to this lies in the question - you have dismissed the question before seeking the answer. As a physicist all the above are correct and are factual - the Earth is tilted at a higher angle to the sun hence days are shorter in the northern hemisphere and longer in the southern- the sun is farthest from the earth at winter as the earths orbit is an elliptical not concentric orbit. The amount of thermal radiation (heat) reaching the earth is less in the northern and more in the southern regions. Lastly the earth was gripped in an iceage for 20,000 years and the next ice age is due almost now in geological time. The earth's core has its own cycle of thermal activity. In fairness the sun's rays are percieved to be colder as the wavelength of light reaching the northern hemisphere is longer - short wavelengths = heat ( i.e Microwaves ) long wavelengths are cooled.

To appreciate the angle of the sun at any time you can try measuring it using a sundial - the shadow of the line is definitely shorter for the same time of day in summer than it is in winter.

Regardless of the sun the wind chill factor is the greatest variant in the temperature we feel. a gentle breeze could affect local temperatures by as much as 5'C or 30%.

Answer 5

Well the tilt theory is correct! In summer the sun (around noon/lunch time) almost gets vertical with the ground, pushing more UV rays down therefore making it way hotter! In the winter time, the earth tilts away from the sun, so the sun is not staying up nearly as long as in the summer, and its not forcing all of the rays in one direct spot. Ok look at it like this.. If you take a flashlight , turn it on and point it toward the ground holding it about one ft or so off the ground. Place your hand under it and you should feel some heat coming off of it. Now lay the flashlight on the floor still on, and place your hand in front of the light again, as you see all of the rays from the flashlight arent as concentrated in one place!

Answer 6

It is not hotter or colder; consider sunspots and solar activity as a possible explanation, but these would be constant for the whole planet, not just yor bit of it or mine! The earth is at a fixed distance from the sun but the poles wobble or oscillate is the ususal answer. However, as we tilt away in winter and are subjected to colder air, it is this air which needs to be warmed before we feel the effects. In the context of your question, however, the temperature differential may simply be down to "it feels colder, therefore it must be!"

We can only estimate the temperature of the sun, and given that man seldom creates anything hotter except for the plasma arc in an ICP-OES our notion of the suns temperature has never been physicaly proven.

Answer 7

It's because in summer, the sun is higher overhead in the day. That's because of the tilt of the earth relative to the sun (sorry, but it's true).

Get a torch and turn the light out. Shine it straight down at the floor. You'll see a circle of light. Now shine it further away, so it hits the floor at an angle. The same amount of light is coming from the torch, but it's more spread out when it hits the floor.

Because the same amount of light is lighting up more floor, each bit of floor gets less light. In other words, it's darker.

Well, heat radiation works exactly the same way as light radiation - it's the same thing really, just a different wavelength.

So...in the little experiment you've just done, substitute heat for light, and you've got your answer!

Answer 8

Distance from the sun has nothing to do with it and is a poular misconception. This is hard to explain, but it is to with the tilt; In our summer the northern hemisphere is tilting towards the sun so the amount of ground that each 'ray' of heat/light covers is smaller and therefore concentrated. In our winter, the northern hemisphere is tilting away so the rays are spread over more acreage and therefore diluted.

Imagine an arrow fired horizontally at a the 'equator' of a football; the point of impact would be smaller than if you shot the same arrow from the same distance, on the same plane but aimed higher up the ball - because of the curve of the ball, the size of the point of impact would be bigger and, believe it or not, this difference is big enough in cosmic terms to make the variances in temperature to which you are referring. On another point, your observation about the height of the sun at certain times of day and at different times of day is erroneous and therefore wholly misleading.

Answer 9

In summer it's hot because sunlight hits the Earth (and hits you) more directly, whereas in winter it hits you more obliquely. This causes that fewer light rays hit you in winter --- and that is what you feel when you say that in winter the Sun is colder.

This is what other answers mean when talking about the 'tilt'. It has nothing to do with the distance between the Earth and the Sun: in fact, in the northern hemisphere winter coincides with the time the Sun is closest to the Earth

Answer 10

You answered your own question. The summer sun feels hotter because the days are longer and the nights are shorter. In the winter the opposite is true-short days and longer nights.
The high and low pressure systems that move accross the land also affect how hot the sun feels.

Answer 11

The sun doesn't change temperature, the earth's axis tilts us further away from the sun in the winter, and consequently we get shorter days and the sun is lower in the sky, in the summer we tilt toward the sun and the days get longer and sun is higher in the sky.

It is the earth's temperature that changes throughout the seasons due to hours of sunlight and height of the sun in the sky, it has nothing to do with the temperature of the sun.