Hot answers tagged

38

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 directions, so you see more colors. See below for the HMS Smoke Polygons for the day, which clearly shows smoke over your region from the intense smoke/wildfire ...


21

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 the plot looks like this: We have no evidence of any significant correlation between the solar cycle and earthquakes or volcanic activity. You won't find ...


18

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: 'The illusion occurs when the moon and sun are separated by a wide angle, so that they are perceived relative to the horizon, as if in a panorama. A panoramic ...


13

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 pointing directly at the sun, then the angle of incidence is equal for all of them and this answer does not apply. For an optic facing its target, the amount of ...


12

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 occur at the end of the midnight sun period by the end of the summer, the first sunset is not complete. Sun at it's highest elevation at midday. (To be ...


11

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 by how exactly weather patterns distribute across the different latitudes. Therefore, a solid answer will require to be supported in data. A good dataset for ...


9

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 pressure). At sunset (and sunrise), since the sunlight is traveling mostly parallel to the surface, it travels through dense atmosphere for considerably longer. ...


9

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 measured from high flying planes. UVC is stopped by the upper layer of the atmosphere so this will never reach the ground,It might be possible to measure some UVC in ...


8

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 (23.5° latitude north) it will happen once every year, on the day of the northern hemisphere solstice (about June 21st). On the Capricorn tropic (23.5° latitude ...


8

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 (and what variance there is happens at source). Total ground level insolation intensity in $\mathrm{Wm^{-2}}$ does change with latitude and seasonal angle of ...


7

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 trajectory. The net result is that rain 'scrubs' the atmosphere clean. Without all these polluting particles to diffuse different wavelengths of the spectrum, the ...


7

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 Earth receives from the Sun in any one time interval. But there's not really much value in such extreme precision anyway. However, it is fairly easy to measure ...


6

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 $\mathrm{Wm^{-2}}$ does change with latitude and seasonal angle of incidence": (image source) Halcyon3k's explanation: Solar energy is measured in watts per ...


5

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 degree. Around depths of 100 feet temperatures start to rise, increasing about 25C/km or 1F/70 feet. First approximation then for zero solar input (effective temp -...


4

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 stronger in New York as compared to Ukraine. Let me offer two lines of evidence that this change is more likely to be related to you and your skin than it is to the ...


4

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 terms to conclude that such a situation will only rarely, or even never, happen. But allowing some reasonable latitude (pardon the pun) in our definitions, we ...


4

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 captured by green house gases in the atmosphere. Suppose Earth's surface temperature is $T_e$ and temperature of the atmosphere is $T_a$. The energy received from ...


4

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 within sunrise and sunset. I personally wouldn't consider that the dividing line between night and day. I consider night to be the period between dusk and dawn ...


4

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 temperature - every degree of temperature rise gives us 7% more water vapour. So if 'adding more sun' increases the temperature then it automatically increases water ...


4

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 influenced by the very cold antarctic currents and high pressure from Hadley cells. 2) That very much depends on location. In general, a warm ocean will be cloudier ...


4

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 of the year not hours of the day, but the basic change is the same: high to low to high Solar Zenith Angle when irradiating a vertical surface leads to an ...


4

The illusion is due to the sun being so far that the difference in angles shown in the drawing would not be noticeable. Imagine two planes where both of them contain the sun and moon, the level plane would be how an observer would see the moon when both the moon and the sun were at the horizon. The tilted plane is how an observer would normally see the moon ...


4

This image from https://www.timeanddate.com/sun/india/mumbai shows that daylight ended at 6:44, so 6:47 was three minutes into civil twilight and pretty much close to daylight. Notice the orange light in the back - I'm assuming that this is a street lamp, which are only turned on at twilight. Most likely the image appears relatively bright because of ...


4

Can a strong solar storm trigger a violent geomagnetic shift? No. Geomagnetic shifts (whether violent or not, whatever that means) are caused by changes in the Earth's core. Solar activity only affects the atmosphere and Earth's surface. The shape of Earth's magnetic field can affect how the solar activity interacts with Earth. For example, the intensity ...


4

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 agree that the solar panel will have to face the north in the southern hemisphere, and the south in the northern hemisphere. This is because that is the direction ...


3

In this case I'd say it's a combination of Rayleigh scattering, Mie scattering and the angle of the sun. Rayleigh scattering is related to the chemical composition of the atmosphere and occurs when the particles causing the scattering are smaller in size than the wavelengths of radiation in contact with them (this is why the sky appears blue most of the ...


3

I think Wikipedia explains quite well. It is the wind that transport the airborne water droplets from a nearby showering cloud. It is quite common in UK especially near the coast which is often very windy. Usually the weather forecast will say that it has scattered shower with sunny spell. https://en.wikipedia.org/wiki/Sunshower


3

The situation in the southern hemisphere is identical to the northern hemisphere, but they occur at different times of the year. In the northern hemisphere the arctic circle is situated at 66.5 degrees North. Likewise in the southern hemisphere, the antarctic circle is situated at 66.5 degrees South. Between each circle and its respective pole 24 hours of ...


Only top voted, non community-wiki answers of a minimum length are eligible