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29 votes

Why clouds are not moving in NASA's video of the Moon passing in front of the Earth?

The clouds can be seen moving but of course it's subtle at first glance. Frame 16: Frame 20:
Adam Caviness's user avatar
26 votes
Accepted

Why clouds are not moving in NASA's video of the Moon passing in front of the Earth?

They are moving, but not fast enough to notice at the distance shown. From the NASA page: These images were taken between 3:50 p.m. and 8:45 p.m. EDT on July 16, showing the moon moving over the ...
gerrit's user avatar
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11 votes

Why clouds are not moving in NASA's video of the Moon passing in front of the Earth?

The image is real, and the clouds are moving, they just move slow, as clouds do. The unnatural appearance arise because they are taken by DSCOVR at an extraordinarily large distance, from a place ...
Camilo Rada's user avatar
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10 votes

How do the pros measure humidity?

The WMO report Instruments and Methods of Observation has a chapter on Measurement of humidity and a separate chapter on Measurement of upper-air pressure, temperature, humidity. The first deals with ...
M Juckes's user avatar
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8 votes
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How do optical satellites detect different leaf types?

Short answer Different plants reflect light at different wavelengths with specific patterns. If you know the reflection pattern of a broad-leaved forest and that of a needle-leaved forest, you can ...
Andrea Massetti's user avatar
8 votes
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Odd Inuksuk-like objects

I can engage in some educated speculation about what you think you see, but I'm confident you were fooled by the shadows in the image, which are caused by a low sun angle and distorted by the terrain. ...
Spencer's user avatar
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8 votes
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Public sources of topographical data of Earth?

This is an interesting and common question, so I'll try to give a good answer here, that I think is a good place, as well as GIS and Open Data SE. First, regarding the format, you will never find data ...
Camilo Rada's user avatar
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7 votes
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How to remove 'silk braid' noise in satellite data?

You ask, How to remove these abnormal value for more precise data? The short answer is that you might be able to make your data look more representative of the natural 'truth', but you will probably ...
Matt Hall's user avatar
  • 11k
7 votes

How to convert mol/m^2 to total mass ( e.g gram, kg etc )?

$\rm \frac{mol}{m^2}$ shows the amount of $\rm{NO_2}$ in the atmosphere over a square meter of surface area - in mols. The molar mass of the $\rm{NO_2}$ is $14+2\cdot 16=46$. It means, the mass of 1 ...
peterh's user avatar
  • 670
7 votes

How do I convert Sentinel-5p / TROPOMI vertical column density to concentration?

The unit mole / m² has dimensions count per area; the unit µg / m³ has dimensions mass per volume. To go from a quantity per area to a quantity per volume, you need to understand some properties of ...
gerrit's user avatar
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7 votes
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Remote sensing of glaciers, season for data collection

Looking around at some random articles, for example Karpilo 2009, Geissler et al 2021, Litt et al. 2019, and Racoviteanu et al 2008 my impression is that researchers primarily use images of the ...
Matt Hall's user avatar
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6 votes
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Need help understanding this satellite image of Larson C ice shelf

I found a natural-color image of the same area: 68.28 South, 60.47 East, North is up, resolution is 130m/px, which makes the whole image about 100 km x 100 km. Looking at the image i'd say that: sea ...
mkadunc's user avatar
  • 176
6 votes

Methane remote sensing?

I found a great paper named Remote Sensing of Particulate Pollution from Space: Have We Reached the Promised Land? and collected some remote sensing instruments doing CH4 measurement in the chart ...
Han Zhengzu's user avatar
  • 2,459
6 votes
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The giant 6,000 km$^2$ iceberg A-68; will ground-truth telemetry supplement satellite tracking data?

I can't imagine a moving object more suitable for remote sensing tracking than Iceberg A-68, with such slow displacement and huge size. So I don't think it will be particularly useful to install any ...
Camilo Rada's user avatar
  • 17.7k
6 votes
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How does ice-penetrating radar "see" through kilometers of ice without being absorbed?

Water molecules do interact with microwaves and in microwave ovens that operate at 900MHZ- 2.5GHz. This Radar instrument operates using Very High Freq Radio Waves at 193MHz [1]. At lower-than-...
potatasbravas's user avatar
6 votes

How do the pros measure humidity?

We use something like an Onset HOBO electronic sensor. They've got logging (and in some cases, networking) built in. They'll typically log both temperature and relative humidity at regular intervals ...
410 gone's user avatar
  • 4,080
6 votes
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Are seismometers over the world "feeling" the small earthquakes caused by air raids and shelling on Gaza Strip?

Bomb explosions are detectable as seismic events, but the energy falls off with distance, so for quakes of less than magnitude 3 you'd have to be with a few 10s of kilometers, depending on your ...
jeffronicus's user avatar
  • 3,487
5 votes

How do optical satellites detect different leaf types?

In general, no, NDVI is not used to derive vegetation type. NDVI is useful for studying phenology, but it won't tell you the type of plant that is being remotely sensed. Good land cover systems use ...
f.thorpe's user avatar
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5 votes
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MODIS Surface Reflectance Data State QA Aerosol Quantity field meaning is unclear

Most likely, climatology means there was no retrieval at all. Bayesian retrievals combine information from an a priori with information from measurements. When the retrieval fails for whatever ...
gerrit's user avatar
  • 11.7k
5 votes

How to remove 'silk braid' noise in satellite data?

Thanks for @Kwinkunks's answer. I have read this paper. And this figure may explain something important. What I have already done is plotting the original data like the first subplot. From Destriped -...
Han Zhengzu's user avatar
  • 2,459
5 votes
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Convert OMI NO2 Vertical Column Density (molecules/cm^2) into Mixing Ratio (ppm)

No, you shouldn't really do that. A vertical column density (VCD) retrieval provides the user with a representation of the total number of molecules over some vertical slice (e.g. the entire ...
f.thorpe's user avatar
  • 13.7k
5 votes

How does ice-penetrating radar "see" through kilometers of ice without being absorbed?

When electromagnetic waves travel through a medium, it can interact with the medium in question. But that interaction depends on the electric properties of the medium. Ice, being a dielectric medium, ...
Mingthondraba Bill's user avatar
5 votes
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Satellite image displaying as panchromatic

An RGB image can not be rendered if you only supply information for one color channel. This is because three channels are needed: Red, Green and Blue. Different software will deal with this invalid ...
Camilo Rada's user avatar
  • 17.7k
4 votes

What is principle of inverse modeling?

To my understanding, the question refers to studies which aim to estimate pollutant emission fluxes using satellite retrievals of atmospheric constituents. Mathematically, this means estimating the ...
jvir's user avatar
  • 391
4 votes

What is a breadboard (retrieval) algorithm in the context of geophysical satellite retrievals/remote sensing?

When determining the retrieval algorithm for a spectrometer that will be built, it is first done on highly mathematical software platforms. The software allows to the best curve approximation fitting ...
f.thorpe's user avatar
  • 13.7k
4 votes

A rough picture about the ground-level ammonia (NH3)

It seems difficult to find a reasonable proxy species for $\mathrm{NH}_3$, since its sources (primarily agriculture) are quite distinct from the sources of more commonly observed pollutants. Some ...
jvir's user avatar
  • 391
4 votes

Why is satellite imagery data delivered as signed 16 bit integers?

Because the surface or top-of-the-atmosphere products are not raw data. Atmospheric corrections have been applied to the raw data and those corrections have been done with a precision that can't be ...
Camilo Rada's user avatar
  • 17.7k
4 votes
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What are the differences between down-looking and side looking radar?

A radar measures the time of arrival of the backscattered signal to infer the distance between the target and the platform (satellite, aircraft, whatever). If two targets are at the same distance from ...
Jean-Marie Prival's user avatar
4 votes
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What is the use of HV or VH polarization in Radar?

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 ...
Reed Espinosa's user avatar

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