# Tag Info

52

The below figure, taken from Wikipedia shows a model of the free fall acceleration, i.e., 'gravity'. The left-most point corresponds to the center of the Earth; then further right at $6.3\cdot1000$ km you are at the Earth's surface; and then further out you move into space. You can follow the blue line for PREM to get an idea of the average (expected) ...

21

This is a companion to the other answer. The other answer gives values for what the acceleration actually is based on knowledge about the composition of the planet. In this answer I want to introduce some of the mathematical tools that allow you to reason about how gravity varies in and around planets. David Hammen's answer, which I think he wrote ...

10

Your question is simple enough, but the answer depends on what exactly you're looking for. Who is emitting where right now? Real-time global monitoring of greenhouse gas emissions with a high spatial resolution is an emerging technology. We have very useful satellites (see Jean-Marie Privals answer), but they have limitations: All existing public ...

9

Given the weather patterns, it looks like Google Earth is generating those cloud overlays from some recent (i.e., the current day) satellite images. That line is suspiciously close to the edge of disc line for Meteosat 8, which is located over the equator at 41.5 °E. I suspect that it's just an artefact of how they're stitching together the various images ...

9

I can imagine a satellite observation-based model that calculates emissions on a spatial basis but I am not sure if our technology is advanced enough to do that accurately. It is. The first satellite designed to measure GHG is GOSAT, from the Japanese space agency, launched in 2009 and still active today. It was followed by Nasa's OCO-2 in 2014. GOSAT ...

7

Make your own numbers... I will take one sample, just change your figures. I have one 4K resolution dron camera. So I can register 3840 x 2160 pixels in one shot. Considering the Earth as an spherical body, the distance from you to the horizon depends on Earth Radius and your height by: Distance = (Radius + height) * Sinus {arc-cosinus [Radius / (Radius ...

6

This is a companion answer to both Erik's and tfb's answers. tfb's answer assumes a uniform density throughout the Earth. This is highly inaccurate. Not to disparage tfb's answer; I've run across physics PhDs who thought that this was the correct model of gravitation inside the Earth. The problem with this model is that the uniform density model is invalid ...

3

This is better suited for English Language &Usage SE, but the word you're looking for is Isochron an imaginary line or a line on a chart connecting points at which an event occurs simultaneously or which represents the same time or time difference (Source: Merriam-Webster) Isochrons are typically used in diagrams rather than maps, for techniques ...

3

If it’s hot enough to alter the groundwater chemistry that is killing the trees, then you would see it in satellite thermal imaging. Remember, tree roots only go down about 20 to 30 feet at the most, so this is all pretty shallow stuff. This is actually quite a strong thermal anomaly. Like you said, the heat alone may have killed the tree/tree roots.the ...

3

Satellite data is relatively new and is likely to be used to compare and refine calculations of emissions by other means rather than used as the principle means for estimating emissions. Consumption based accounting is the main way we get the declared emissions, including methane, nitrous oxides and carbon monoxide and others as well as CO2, for the world ...

3

In the case of a ground looking radar, the cross-polarized signals HV and VH generally increase with surface roughness. For example, dense vegetation is one of the more depolarizing surface types because the polarization orientation of the emitted beam is scrambled over the course of multiple scattering interactions within the canopy before returning to the ...

2

In November 2008 neutrino tomography was used to measure Earth's mass. A paper was published in journal Nature. The data was captured by the South Pole’s IceCube Neutrino Observatory. In November 2013 IceCube announced it had discovered 28 neutrinos that likely originated outside the Solar System. The neutrinos that the IceCube detector had “caught” came ...

2

Answer to that one: What you describe is a measurment, not a calculation. The measurment you describe varies the potential difference at a satellites Langmuir probe. The potential difference then attracts or deflects ions, and deflects or attracts electrons. Those electrons and ions are the current being picked up by the Langmuir probe. Then follows a ...

1

It depends... What do you understand as 24 hours daylight? Sun should be visible? There should be light, even if the Sun is not visible? There are different interpretations: Astronomical Twilight:Astronomical twilight is the darkest of the 3 twilight phases. It is the earliest stage of dawn in the morning and the last stage of dusk in the evening. ...

1

If you can get one dumpy level (surveyor level), it is very easy. Place the dumpy level in one flat area and take the level from one point and transfer to another one. Try to do it as far as possible. At this stage it is suppose that you have 2 points on the same level. Then place the dumpy level as close as you can to one of this points and transfer again....

1

Apparently, the IERS publishes values for each 0 h of UTC in their bulletins. I myself thought otherwise, but I recently noticed, in a geodesy exam, that they mentioned UTC for the daily parameters. Upon closer look at the Bulletins themselves, I was able to confirm this: Although using UT1 instead of UTC for interpolation should cause only tiny errors, ...

1

Complementing @Gimelist and @Graipher answers... Regarding your title question... The CERN magnetic field value it is considered on the CERN ring itself, 5 meters away it is just 20mT... It is just physics... just check this link. So it is dropping with the inverse cube of the distance. On the top of the CERN is becoming... (100 meters away) around 8uT... ...

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