40
votes
Accepted
Why were both the sun and the moon red today?
Smoke. There was significant smoke across the USA, which attenuated the light from the sun/moon due to increased scattering. The smoke particles effectively cause the light to reflect in different ...
- 13.5k
33
votes
In the northern hemisphere summer, why are places in the north cooler than those in the south?
The image below (apparently from "physicalgeography.net" is somewhat instructive:
Notice that even in the middle of summer, India (at about 30 °N) still gets slightly more sun than the ...
- 797
21
votes
Is there any correlation between Grand Solar Minimums (GSM) and earthquakes?
The main proxy that we have of past solar intensity comes from its proven correlation to the number of sunspots, which have been recorded since the invention of the telescope in the early 1600's. And ...
- 17.6k
21
votes
What is this Sun and moon photographic anomaly?
The apparent anomaly, known as the Lunar Terminator or Moon Tilt Illusion, is indeed a matter of perspective. A brief explanation can be found here: http://chrisjones.id.au/MoonIllusion/
The essence: ...
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14
votes
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Why does the intensity of sunlight depend on your latitude?
As noted in the comments, this answer applies to things like sun-bathing and solar panels, but it does not apply so much to a specific point-receptor like an eyeball. If all objects in question are ...
- 351
13
votes
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Is there an instance where the sun sets or rises partly, then return back?
Yes, such sunrises happens every year at the beginning and end of the polar nights at high latitudes. One can have a few days with a glimpse of the sun but disqualified sunsets and sunrises.
Sunsets ...
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12
votes
In the northern hemisphere summer, why are places in the north cooler than those in the south?
Hours of sunlight are not the only factor that determines insolation (solar energy at the surface).
Thought experiment: spread a bed sheet on the floor, switch the lights off, and shine a flashlight ...
11
votes
Accepted
What are the sunniest places on Earth? (including oceans)
It is an interesting question, and despite that latitude is the main control of the amount of solar radiation that reaches the top of the atmosphere at a given location, the answer will be determined ...
- 17.6k
9
votes
Accepted
Why can I look directly at the sun during a sunset but not at noon?
At Noon, sunlight is coming from nearly directly above you, and goes through ~2 miles (4km) of reasonably dense atmosphere to reach you (Atmospheric pressure at 2 miles is about one half of sea level ...
- 206
9
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To what extent do the levels of UVA, UVB and UVC radiations on the earth surface increase during solar flares?
During a powerful solar flare the amount of x-ray radiation can increase up to 110% in the boundry layer of the atmosphere/space,very little of this will reach the earths surface but it can be ...
- 1,868
8
votes
What time and date is the sun directly overhead a given place on Earth?
Having the sun directly overhead can happen only between the Cancer and Capricorn tropics. That is, only the places between 23.5° of latitude north and 23.5° of latitude south.
On the Cancer tropic (...
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8
votes
What is this Sun and moon photographic anomaly?
Here my wife holds a globe with the moon in view. I carefully processed in a bit-mode to find the curve of light on the globe and drew perpendicular lines. Plainly we can see that the moon-lite side ...
- 81
8
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Does the amount of UVA radiations one receives depend on the day ot the year?
UVA passes through the atmosphere without losing much intensity, so per quote one it's intensity doesn't change, nor does it's magnitude as a percentage of total insolation vary, much, during the year ...
- 4,260
8
votes
Accepted
Where does the sun set?
Where it sets depends on 1) your latitude and 2) the Sun's declination, which varies throughout the year between -23° (December) and +23° (June). Consider the following pictures, taken from A Quick ...
- 748
7
votes
Is there any way to measure the amount of radiation the earth receives from the sun?
Your understanding is half correct. Yes, we can measure the amount of radiation the Earth receives from the Sun.
Yes, it is difficult to get an extremely precise measure of how much radiation the ...
- 4,090
7
votes
Accepted
Calculate the maximum power angle of a solar panel (photovoltaics)
This question can be answered in many different ways that take into account, or ignore, the many factors that affect the total output of a fix solar panel over a year.
In general, all answers will ...
- 17.6k
6
votes
Accepted
The sun sometimes appears pure white after rainfall, how can this be explained?
When it rains the raindrops nucleate around aerosol particles of salt, dust, clay, soot, dimethyl sulphide, etc. In addition a falling raindrop may pick up any particulate matter that may be in its ...
- 14.2k
6
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Does the amount of UVA radiations one receives depend on the day ot the year?
Reddit user and r/EarthScience mod Halcyon3k pointed me to the following visualization that nicely illustrates Ash's great answer on the fact that "total ground level insolation intensity in $\...
6
votes
Accepted
Why do solar panels capture less energy at higher latitudes?
If that is indeed the case, then what is the real reason why solar panels capture less energy at higher latitudes?
In a nutshell, air mass.
You aren't going to get a nice suntan (or a not so nice ...
- 23.2k
5
votes
Accepted
How can we calculate the temperature of the atmosphere, including the greenhouse effect?
One can account for greenhouse gas effect for Earth's temperature in simple energy balance model in following manner.
Assume that fraction $f$ of longwave radiation emitted by Earth's surface is ...
- 797
5
votes
Accepted
How much of one day can be considered nighttime, on average?
To further clarify, assume we are on the equator, I want to know how long a time, as a percentage, you could consider to be nighttime on Earth, with the points in time separating night and day being ...
- 23.2k
5
votes
calculate UV index in vertical plane
According to Ultraviolet Radiation, Human Health, and the Urban Forest it would seem at least the general shape you obtained is correct:
Here they tracked the irradiance at noon over different months ...
- 51
5
votes
Accepted
If the Sun disappeared, how long would it take for the Earth to freeze beyond excavatable depths?
Step wise approach:
Right now when the surface is very cold, the frost depth here (Alberta, -40 min winter temps) can reach 8 feet. Below about 30 feet seasonal temperature changes are under a ...
4
votes
Sun's Highest Point on June 21
Well, kind of, depending on what you really mean.
We're being rather vague with our terms, and so it shouldn't be surprising if the answer doesn't meet our expectations.
We could interpret all these ...
- 3,548
4
votes
The sun sometimes appears pure white after rainfall, how can this be explained?
The sky appears white because immediately after the rain stops and the clouds have started to dissipate, there are often water aerosols (i.e. diffuse clouds) still lingering in the atmosphere. Unlike ...
- 813
4
votes
Difference in sun activity between two towns (Eastern and Western hemispheres)
I believe this is biology related, not weather related
I think your story is a bit anecdotal because there is no measurable evidence that the sunlight energy deposited into your skin is actually ...
- 3,366
4
votes
What are the sunniest places on Earth? (including oceans)
1) No, there are many places in the ocean that receive more sunlight hours than many deserts. For instance, the west coasts of southern Africa and central South America. These locations are ...
- 348
4
votes
Sun's Effect on Water Vapor in the Air
You need to define what you mean by 'adding more sun'. I'm asuming you mean 'increase the solar constant'.
The amount of water vapour in the air is, as a first order approximation, related to ...
- 1,082
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