6 ms·

OK so dumb guy here needs someone to explain this chart I keep seeing and not understanding. [1] It shows average temperatures month by month, peaking in summe

OK so dumb guy here needs someone to explain this chart I keep seeing and not understanding. [1] It shows average temperatures month by month, peaking in summer months, cooler in winter months. As expected. Except that the graph says this is a global mean temperature, not just the northern hemisphere. I would expect that the earth, on average, from north pole to equator to south pole, would, on average day, have about the same mean temperature, as it gets the same amount of total sunlight overall, regardless of the tilt of the earth. We're essentially on a sphere, and it gets the same sunlight coverage even though some points get more light than others. I mean it's not like the earth gets less overall sun just because it's winter in the north. So for whatever reason the entire earth is warmer when the northern hemisphere is experiencing summer? Am I interpreting that right? How is that possible, and what am I failing to take into account? Does it have something to do with the elliptical orbit of the earth, and possibly that our closest yearly approach to the sun just happens to align with summer months in the northern hemisphere? [1] https://media.nature.com/lw767/magazine-assets/d41586-023-02552-2/d41586-023-02552-2_25932032.png https://media.nature.com/lw767/magazine-assets/d41586-023-02...

adaml_623 3y ago
Yes. Northern and Southern seasons are not the same length due to the orbit. Also the proportion of land to ocean is very different which I think makes a big difference.
asah 3y ago
not necessary: a lot of heat (energy) radiates out into space or is blocked from doing so but greenhouse gasses... and a lot of energy is sequestered into solid matter... or not...
bad_alloc 3y ago
> Am I interpreting that right? Yes. > How is that possible, and what am I failing to take into account? There are factors like that most of the landmass is in the northern hemisphere, we are in a strong El Nino, ships have to burn fuel with less sulphur and so on. Right now the factors involved are unclear but there is an unsettling possibility: The Earths climate might drastically and quickly change at so called tipping points, after which a new balance becomes the norm. This new balance may or may not be hospitable or even habitable for us. > Does it have something to do with the elliptical orbit of the earth, and possibly that our closest yearly approach to the sun just happens to align with summer months in the northern hemisphere? Nope, our orbit is very round and if this was a major factor we'd see it in historic data.
hattmall 3y ago
2x the landmass is in northern hemisphere, so there's less moderation from evaporation in NH summer.
- lordfrito 3y ago
  OK the landmass thing a few people pointed out. I can buy into this, but it's still a bit confusing. What does 'moderation' mean? The solar energy has to go somewhere, I'm assuming that's temperature. Are you saying it's not going into temperature, but instead being stored some otherway (like evaporation causing an increase in potential energy as the molecules rise?). To me it's a question of energy input from sun - energy reflected and radiated out. Something like temperature = constant * (energy from sun - energy reflected - energy radiated) Maybe the earth reflects more energy due to more water / less land in the southern hemisphere?
  - NotYourLawyer 3y ago
    Antarctica is a huge white block of ice too. That reflects a lot of sunlight.
  - AmpsterMan 3y ago
    It's more that every substance has a specific heat capacity. That is, how much energy it takes to raise 1 g of that substance one degree Celsius. Water happens to have some of the highest specific heat capacities. Therefore, the south can "store" more energy in the hot months, and release that same energy in the cool months better than the north can
    - lordfrito 3y ago
      Yep forgot about this, explanation makes perfect sense. Thank you. Thank god we have these big wet heat sinks available to help keep climate stable.
  - MooMooMilkParty 3y ago
    There is actually an energy cost to evaporation which takes some of that energy: https://en.wikipedia.org/wiki/Enthalpy_of_vaporization https://en.wikipedia.org/wiki/Enthalpy_of_vaporization So, this, as well as ocean mixing is how the surface temperature is "moderated", in addition to the heat capacity that others have brought up.
danw1979 3y ago
Because the landmass is split 68/32 north/south and sunlight on the land has a greater effect on atmospheric temperature than the sea ?
deredede 3y ago
From what I remember, this is because there is more land in the northern hemisphere and more ocean in the southern hemisphere, and water has better thermal capacity than soil.
MooMooMilkParty 3y ago
Not a dumb question at all! The main reason is because there is much more land mass in the northern hemisphere than in the southern, and land tends to heat up more than ocean. You can actually see how this effect balances out on this site: https://climatereanalyzer.org/clim/t2_daily/ https://climatereanalyzer.org/clim/t2_daily/ If you look at the annual temperature range for the northern hemisphere (NH) it has a range >10C, while the southern hemisphere has a range ~5C. You can read more about this here: https://www.carbonbrief.org/guest-post-why-does-land-warm-up-faster-than-the-oceans/ https://www.carbonbrief.org/guest-post-why-does-land-warm-up...
- grammers 3y ago
  Thanks for explaining, this made my day!
Alupis 3y ago
Earth's Hottest Month** ** Since 1850 Why do these articles always try to sensationalize things? You lose credibility when you create clickbait headlines. My understanding is temperatures recorded before about 1880 are unreliable[1]. This article does not provide a source for where their data comes from. [1] https://climate.nasa.gov/faq/21/why-does-the-temperature-record-shown-on-your-vital-signs-page-begin-at-1880/#:~:text=The%20oldest%20continuous%20temperature%20record,temperatures%20for%20the%20entire%20planet https://climate.nasa.gov/faq/21/why-does-the-temperature-rec....
KineticLensman 3y ago
The closest approach to the Sun is actually in January, the Northern Hemisphere winter. But that is when the axial tilt means that the north pole spends most time pointing away from the Sun, hence winter.

adaml_623 3y ago

Yes. Northern and Southern seasons are not the same length due to the orbit. Also the proportion of land to ocean is very different which I think makes a big difference.

asah 3y ago

not necessary: a lot of heat (energy) radiates out into space or is blocked from doing so but greenhouse gasses... and a lot of energy is sequestered into solid matter... or not...

bad_alloc 3y ago

> Am I interpreting that right? Yes. > How is that possible, and what am I failing to take into account? There are factors like that most of the landmass is in the northern hemisphere, we are in a strong El Nino, ships have to burn fuel with less sulphur and so on. Right now the factors involved are unclear but there is an unsettling possibility: The Earths climate might drastically and quickly change at so called tipping points, after which a new balance becomes the norm. This new balance may or may not be hospitable or even habitable for us. > Does it have something to do with the elliptical orbit of the earth, and possibly that our closest yearly approach to the sun just happens to align with summer months in the northern hemisphere? Nope, our orbit is very round and if this was a major factor we'd see it in historic data.

hattmall 3y ago

2x the landmass is in northern hemisphere, so there's less moderation from evaporation in NH summer.

lordfrito 3y ago
OK the landmass thing a few people pointed out. I can buy into this, but it's still a bit confusing. What does 'moderation' mean? The solar energy has to go somewhere, I'm assuming that's temperature. Are you saying it's not going into temperature, but instead being stored some otherway (like evaporation causing an increase in potential energy as the molecules rise?). To me it's a question of energy input from sun - energy reflected and radiated out. Something like temperature = constant * (energy from sun - energy reflected - energy radiated) Maybe the earth reflects more energy due to more water / less land in the southern hemisphere?
- NotYourLawyer 3y ago
  Antarctica is a huge white block of ice too. That reflects a lot of sunlight.
- AmpsterMan 3y ago
  It's more that every substance has a specific heat capacity. That is, how much energy it takes to raise 1 g of that substance one degree Celsius. Water happens to have some of the highest specific heat capacities. Therefore, the south can "store" more energy in the hot months, and release that same energy in the cool months better than the north can
  - lordfrito 3y ago
    Yep forgot about this, explanation makes perfect sense. Thank you. Thank god we have these big wet heat sinks available to help keep climate stable.
- MooMooMilkParty 3y ago
  There is actually an energy cost to evaporation which takes some of that energy: https://en.wikipedia.org/wiki/Enthalpy_of_vaporization https://en.wikipedia.org/wiki/Enthalpy_of_vaporization So, this, as well as ocean mixing is how the surface temperature is "moderated", in addition to the heat capacity that others have brought up.

danw1979 3y ago

Because the landmass is split 68/32 north/south and sunlight on the land has a greater effect on atmospheric temperature than the sea ?

deredede 3y ago

From what I remember, this is because there is more land in the northern hemisphere and more ocean in the southern hemisphere, and water has better thermal capacity than soil.

MooMooMilkParty 3y ago

Not a dumb question at all! The main reason is because there is much more land mass in the northern hemisphere than in the southern, and land tends to heat up more than ocean. You can actually see how this effect balances out on this site: https://climatereanalyzer.org/clim/t2_daily/ https://climatereanalyzer.org/clim/t2_daily/ If you look at the annual temperature range for the northern hemisphere (NH) it has a range >10C, while the southern hemisphere has a range ~5C. You can read more about this here: https://www.carbonbrief.org/guest-post-why-does-land-warm-up-faster-than-the-oceans/ https://www.carbonbrief.org/guest-post-why-does-land-warm-up...

grammers 3y ago
Thanks for explaining, this made my day!

Alupis 3y ago

Earth's Hottest Month** ** Since 1850 Why do these articles always try to sensationalize things? You lose credibility when you create clickbait headlines. My understanding is temperatures recorded before about 1880 are unreliable[1]. This article does not provide a source for where their data comes from. [1] https://climate.nasa.gov/faq/21/why-does-the-temperature-record-shown-on-your-vital-signs-page-begin-at-1880/#:~:text=The%20oldest%20continuous%20temperature%20record,temperatures%20for%20the%20entire%20planet https://climate.nasa.gov/faq/21/why-does-the-temperature-rec....

KineticLensman 3y ago

The closest approach to the Sun is actually in January, the Northern Hemisphere winter. But that is when the axial tilt means that the north pole spends most time pointing away from the Sun, hence winter.