# Why is summer 'hotter' then winter **URL:** \ **Category:** Factual Questions\ **Created:** [July 25, 2004, 11:26pm UTC](https://boards.straightdope.com/t/why-is-summer-hotter-then-winter/256858 "2004-07-25T23:26:50Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![kanicbird](https://avatars.discourse-cdn.com/v4/letter/k/5f8ce5/32.png) [@kanicbird](https://boards.straightdope.com/u/kanicbird)\ **Post date:** [July 25, 2004, 11:26pm UTC](https://boards.straightdope.com/t/why-is-summer-hotter-then-winter/256858/1 "2004-07-25T23:26:50Z")
I was taught that the angle of the sun’rays’ were more direct in the summer, which I understand. But I have never heard that the longer days in the summer could be a factor. How importaint is that factor? and any other factors that should be considered? ---
**Author:** ![ultrafilter](https://avatars.discourse-cdn.com/v4/letter/u/3d9bf3/32.png) [@ultrafilter](https://boards.straightdope.com/u/ultrafilter)\ **Post date:** [July 26, 2004, 12:19am UTC](https://boards.straightdope.com/t/why-is-summer-hotter-then-winter/256858/2 "2004-07-26T00:19:36Z")
If I’m not mistaken, the longer days are a consequence of the angle of the earth with respect to the sun. Here’s a question: do Australian days get shorter as American days get longer? ---
**Author:** ![Bewildebeest](https://avatars.discourse-cdn.com/v4/letter/b/779978/32.png) [@Bewildebeest](https://boards.straightdope.com/u/Bewildebeest)\ **Post date:** [July 26, 2004, 1:04am UTC](https://boards.straightdope.com/t/why-is-summer-hotter-then-winter/256858/3 "2004-07-26T01:04:17Z")
Well, Australian days get longer as North American days get shorter anyway. ---
**Author:** ![Cunctator](https://avatars.discourse-cdn.com/v4/letter/c/43a26b/32.png) [@Cunctator](https://boards.straightdope.com/u/Cunctator)\ **Post date:** [July 26, 2004, 1:21am UTC](https://boards.straightdope.com/t/why-is-summer-hotter-then-winter/256858/4 "2004-07-26T01:21:59Z")
Our days are certainly getting longer at the moment. Just over a month ago when we had the winter solstice on 21 June, Sydney had its shortest day with total daylight of 9 hours and 53 minutes (sunrise 7.01am, sunset 4.54pm). Today (26 July) total daylight has increased to 10 hours and 20 minutes (sunrise 6.52 am, sunset 5.12pm). ---
**Author:** ![Dahnlor](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dahnlor/32/533_2.png) [@Dahnlor](https://boards.straightdope.com/u/Dahnlor)\ **Post date:** [July 26, 2004, 1:59am UTC](https://boards.straightdope.com/t/why-is-summer-hotter-then-winter/256858/5 "2004-07-26T01:59:52Z")
> [@kanicbird](#): > > I was taught that the angle of the sun’rays’ were more direct in the summer, which I understand. But I have never heard that the longer days in the summer could be a factor. How importaint is that factor? and any other factors that should be considered? Considering that the angle of light goes hand-in-hand with length of day, I’d say both factors are equally important. The light hitting the surface at a steeper angle is hotter because it is going through less atmosphere to get there, and the longer days allow the heat to build up and stay around longer. D ---
**Author:** ![Laughing\_Lagomorph](https://avatars.discourse-cdn.com/v4/letter/l/6bbea6/32.png) [@Laughing\_Lagomorph](https://boards.straightdope.com/u/Laughing_Lagomorph)\ **Post date:** [July 26, 2004, 2:01am UTC](https://boards.straightdope.com/t/why-is-summer-hotter-then-winter/256858/6 "2004-07-26T02:01:41Z")
> [@ultrafilter](#): > > If I’m not mistaken, the longer days are a consequence of the angle of the earth with respect to the sun. Here’s a question: do Australian days get shorter as American days get longer? Yes. The shortest day of the year in the Northern Hemisphere is the longest day of the year in the Southern Hemisphere, and vice versa. ---
**Author:** ![Freddy\_the\_Pig](https://avatars.discourse-cdn.com/v4/letter/f/a587f6/32.png) [@Freddy\_the\_Pig](https://boards.straightdope.com/u/Freddy_the_Pig)\ **Post date:** [July 26, 2004, 2:31am UTC](https://boards.straightdope.com/t/why-is-summer-hotter-then-winter/256858/7 "2004-07-26T02:31:03Z")
> [@kanicbird](#): > > I was taught that the angle of the sun’rays’ were more direct in the summer, which I understand. But I have never heard that the longer days in the summer could be a factor. How important is that factor? The two effects are not readily separated. The Sun’s angle of elevation above the horizon (azimuth) changes throughout both summer and winter days. However, here is one way to think about it: At a typical middle latitude, you’ll receive about [four times as much solar radiation in summer as in winter](http://www.yorku.ca/mcdade/nats1750/ASS2.html), but your day will only be 1.67 times as long (roughly 15 hours versus 9). So obviously the angle of solar elevation is very important. > [@](#): > > and any other factors that should be considered? The earth is closer to the Sun during northern hemisphere winter, which increases insolation by a factor of about 1.07. Obviously this is drowned out by the other factors. Local considerations such as nearby mountains or water will also effect the relative intensity of summer and winter at your location. ---
**Author:** ![Freddy\_the\_Pig](https://avatars.discourse-cdn.com/v4/letter/f/a587f6/32.png) [@Freddy\_the\_Pig](https://boards.straightdope.com/u/Freddy_the_Pig)\ **Post date:** [July 26, 2004, 4:13am UTC](https://boards.straightdope.com/t/why-is-summer-hotter-then-winter/256858/8 "2004-07-26T04:13:48Z")
D’oh, replace “azimuth” with “altitude” in the above post. ---
**Author:** ![Jeff\_Lichtman](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jeff_lichtman/32/1531_2.png) [@Jeff\_Lichtman](https://boards.straightdope.com/u/Jeff_Lichtman)\ **Post date:** [July 26, 2004, 6:49am UTC](https://boards.straightdope.com/t/why-is-summer-hotter-then-winter/256858/9 "2004-07-26T06:49:38Z")
> [@Dahnlor](#): > > Considering that the angle of light goes hand-in-hand with length of day, I’d say both factors are equally important. The light hitting the surface at a steeper angle is hotter because it is going through less atmosphere to get there, and the longer days allow the heat to build up and stay around longer. A minor correction: the amount of atmosphere the light goes through has little to do with why it’s hotter in summer than in winter. The main effect is that the intensity of the light is proportional to the sine of the angle of the light to the ground. For example, light hitting the ground at 90 degrees (perpendicular to the surface) is about 41% brighter than the same light hitting the ground at 45 degrees. Even if there were no atmosphere, the surface of the earth would be hotter in summer than in winter.