Kerala Cafe

[The Adventurer]

Uhm...i got a doubt regading the point that clouds city lights dont light up clouds.

Maybe i'm wrong...but have any of you flown from hyd to kochi at night over blore?
i've done so a couple of times and i've always noticed a yellowish tint in the clowds below(i get to know its blore when the screen shows the rooute and position)

[RKPV]

nice piece of information here ! Thanks PPJ

But, I believe since it is opaque , clouds will reflect the light. And the satellite may not be in a 90 degree position to the place while shooting IR rays. And in the map ,some UAs like Kottayam are not at all noticeable and there is some unexpected lights above the sea near Tuticorin (Thuthukkudy port) area. It clarifies that there is some valid points in Aslesh's 'cloud' theory too.

Originally Posted by PPJ

Ok.
1. You cannot compare google maps and nasa image. google map is terrestrial photos i.e. photos taken in daytime few kms above surface of earth. Here you can get images of clouds trees and all those things. The satellite photo is taken outer space. The satellite has various imaging techniques. The above image of course not for weather imaging.

2. Regarding light. Objects are visible to satellite in visible spectrum only in daytime where is sun is the light source. The artificial light source in earth surface is weak and cannot travel much distance, They die out inside earth atmosphere. The IR part of the light travels more distance than visible part since their wavelength is larger. This is the same reason why we have all warning signals are in red is our daily lives because it can be seen in large distances.

3. Clouds. Clouds actually block the view. Any light and ir source it will mask them. If there is cloud it effectively shows up darker in the satellite image. Clouds are not transparent bodies. They are near to opaque in transmission of light. More importantly city lights cannot light up a cloud above it!. here in this case they would have took photos when cloud is not there. This photo is not made in a day anyway and I am sure they have removed the clouds. Otherwise it would have been seen in oceans since moonlight and starlight will reflect them.

4. More importantly most or all of the images from satellites are reconstructed images after applying filters. Usually there will be a couple of spectrometers, CCD etc and the final image u see is actually animated image based on the readings of the various instruments.

I have personally worked on these instruments and very confidently say its not a photo that comes in a click. In fact no satellite comes in a click. It undergoes lot of post processing and the final image is more of a interpolation of data.

Here is a better link to give clear background of the project.

http://earthobservatory.nasa.gov/IOTD/view.php?id=79803
http://earthobservatory.nasa.gov/Features/IntotheBlack/

[ajithv]

[sudheeshnairs]

Gets busy with life Dileep. Life in Bangalore is getting irritating. All the roads are dug up and left like that for months with nobody to care. So daily an average drive of 4 hours on average for 40-50 km. Nattilayirunnenkil TVM il ninnum EKM ethiyene.

Also lots of trips to TVM. During Deepavali I took my Indica back to TVM, through EKM. One of my closest friend is from Kochi, he was here in Bangalore to get a custom made steel bumper for his 4x4 Bolero (for fitting winch) and buy a 21 gear mountain bike. So had to drive via EKM carrying those stuff by folding rear seats.

I need to post pics of both my trips to TVM, via TN and via KL. While I took some 10-11 hours in my Skoda Rapid via TN, I took some 19 hours (Including a fast bath and food at my friend's Kaloor residence and buying/changing two new tyres at Palarivattom).

Originally Posted by DileepKS

കൊറച്ചെവ്സം കണ്ടില്ലല്ലോ. എങ്കടാ പോയേർന്നെ?

[ajithv]

Originally Posted by Malayaali

റേഷൻ കടയിൽ ഡോളർ കൊടുക്കേണ്ടി വരുമല്ലോ!



Link

ഇതൊക്കെ എന്ത്.....മനോരോഗിയോടാണ് കളി...അല്ല പിന്നെ.

[Prasanth_KCV]

Source FB

[Prasanth_KCV]

[PPJ]

Originally Posted by RKPV

nice piece of information here ! Thanks PPJ

But, I believe since it is opaque , clouds will reflect the light. And the satellite may not be in a 90 degree position to the place while shooting IR rays. And in the map ,some UAs like Kottayam are not at all noticeable and there is some unexpected lights above the sea near Tuticorin (Thuthukkudy port) area. It clarifies that there is some valid points in Aslesh's 'cloud' theory too.

Actually in raw images, clouds if any, would be visible in satellite image depending on how sensitive the sensors are. And they are visible not due to the light below but from the reflected light from moon and those of stars. In post processing they would be filtering out these clouds. About the IR and cloud there are detailed article in NASA web.

BTW Kottayam UA isnt big anyway to be seen lit like other cities. Whole dist pop is 19+ lakh and UA pop is 3+ lakh. It is neither industrialized or densly pop as kollam. Also more green cover absorbs heat and radiations. And there may be several other factors too. Tuticorin is a port and obviously it will be lit up!. You may feel some part is into the sea since whole of land sea border will be dark everywhere since all the constructions and lights stops before 50-200(or even more) metres before sea typically except for ports. I dont see anything which doesnt match with reality. And pioneers of space like NASA will not be putting incorrect images.

For those who didnt read the link
"This new global view and animation of Earth’s city lights is a composite assembled from data acquired by the Suomi National Polar-orbiting Partnership (Suomi NPP) satellite. The data was acquired over nine days in April 2012 and thirteen days in October 2012. It took satellite 312 orbits and 2.5 terabytes of data to get a clear shot of every parcel of Earth’s land surface and islands. This new data was then mapped over existing Blue Marble imagery to provide a realistic view of the planet."

[DileepKS]

See this link for information on how the city lights information is obtained.

Then see this link to see the technical details.

The result of this effort can be downloaded from the first link, or better, seen on Google earth. You need to navigate down Gallery->NASA->Earth City lights.

This information is filtered and presented based on the research, and pretty accurate to indicate urbanization. See the third page of second link for information on how they filter each urban region to find the actual urbanization

To correct for this "blooming" effect, the Goddard team zoomed in on the lights emanating from individual cities, effectively isolating them from the larger, continental image. Using computers, they then lowered the overall brightness levels of the city image. The blob of lights representative of the given metropolis would begin to shrink on the outside in a manner similar to an evaporating puddle of water." We scale back on the brightness levels of the imaging data, until the perimeter stops shrinking on the outside and the interior lights of the city begin to break up," Imhoff says. "At that point we stop."

The India image is a different one. It is prepared just to refute the Diwali lights hoax. The proper urbanity filtering was apparently not done on this image. You should remember that the imaging is visible and IR. Our landmass was pretty warm (25-30 deg) in November, making it quite bright on IR.

In contrast to what Aslesh said, the cloud cover actually REDUCES the brightness. So, it is conceivable that Kottayam area had cloud cover (or had lower overall temperature) to make it dark in the image.

The point is, the posted image is not subjected to the normal "urbanity detection" filter of NASA. It is just a specifically produced image to refute the hoax. It is also plausible that they let it a bit brighter, just to emphasis things.

The correct urbanity filtered information is accessible from Google Earth. I am NOT posting it here now. I had posted it sometime back, had a heated discussion (and got brigged).

hope it clears the air a bit

[thanseem]

intesting theories! would like to know effect of load sheddings too..

[thanseem]

Originally Posted by Prasanth_KCV

Source FB

the fourth row was most common during my school days..

[PrateekN]

Nice justification there but not good enough to convince someone that there can be so much "brightness" around Kollam all the way to CGNR when KTYM_CHGRY_TVLA literally looks blacked out. FYI, the latter stretch is much more heavily urbanized and densely populated than most areas in the former.Something wrong there seriously.

Originally Posted by PPJ

Actually in raw images, clouds if any, would be visible in satellite image depending on how sensitive the sensors are. And they are visible not due to the light below but from the reflected light from moon and those of stars. In post processing they would be filtering out these clouds. About the IR and cloud there are detailed article in NASA web.

BTW Kottayam UA isnt big anyway to be seen lit like other cities. Whole dist pop is 19+ lakh and UA pop is 3+ lakh. It is neither industrialized or densly pop as kollam. Also more green cover absorbs heat and radiations. And there may be several other factors too. Tuticorin is a port and obviously it will be lit up!. You may feel some part is into the sea since whole of land sea border will be dark everywhere since all the constructions and lights stops before 50-200(or even more) metres before sea typically except for ports. I dont see anything which doesnt match with reality. And pioneers of space like NASA will not be putting incorrect images.

For those who didnt read the link
"This new global view and animation of Earth’s city lights is a composite assembled from data acquired by the Suomi National Polar-orbiting Partnership (Suomi NPP) satellite. The data was acquired over nine days in April 2012 and thirteen days in October 2012. It took satellite 312 orbits and 2.5 terabytes of data to get a clear shot of every parcel of Earth’s land surface and islands. This new data was then mapped over existing Blue Marble imagery to provide a realistic view of the planet."

[Aslesh]

True. That doesn't explain it. I am not interested in going rounds again and again because that picture speaks by itself.

If you have travelled to via MC road you cannot believe how Kottayam-Thiruvalla can be dark. It is one of most built up stretches in Kerala. It is foolish to say that Kottayam is darker because Kottayam UA has less population. Kottayam district has Changanassery UA too. In that case Pathanamthitta district do not have a UA. There is no UA in eastern parts Kollam. How are they seen as bright? There is much more disparity when we check south of Kollam.

This picture is not much reliable to compare urban areas at least in Kerala.

[DileepKS]

Originally Posted by thanseem

intesting theories! would like to know effect of load sheddings too..

Did you read the article? I guess not. Please do.

[Vinu86]

Originally Posted by The Adventurer

Uhm...i got a doubt regading the point that clouds city lights dont light up clouds.

Maybe i'm wrong...but have any of you flown from hyd to kochi at night over blore?
i've done so a couple of times and i've always noticed a yellowish tint in the clowds below(i get to know its blore when the screen shows the rooute and position)

I used to travel between HYD and COK once in every two months or so. But most of my trips used to be during day.

I thought the city down was Coimbatore. I used to fly by Indigo or Spicejet and neither had personal TVs in economy class.

[PPJ]

Originally Posted by PrateekN

Nice justification there but not good enough to convince someone that there can be so much "brightness" around Kollam all the way to CGNR when KTYM_CHGRY_TVLA literally looks blacked out. FYI, the latter stretch is much more heavily urbanized and densely populated than most areas in the former.Something wrong there seriously.

Kottayam tvla stretch is not continuously populated first of all. Quite evident from google maps. Its around 2km width its very dense with breaks between which is exactly shown in the image with 3-4 discontinous bright areas. Towards west side of this narrow stretch its purely agricultural land which shows up as black in the image. Towards east its sparsely densed which is shown as some discontinuous spots and lines.. In case of kollam pop is evenly distributed and hardly there is big gaps like in kottayam. If u see after chengannur enter kollam district whole of the district is criss crossed with roads which u wont find in kottayam. This is not to compare kottayam and kollam, just to look at the geographical facts.

For me it matches reality and dont have any doubts over the results. NASA wont do stupid mistakes when they are capable of accurately measuring luminosity of stars millions of light years away!.

I am done with it!.

[Aslesh]

It doesn't enter Kollam from Chengannur. Between Chengannur(Alappuzha district) and Kottarakkara there is Pathanamthitta district. There is criss cross roads in Kottayam district too if u check the same google map. There is no way Pathanamthitta is bright but Kottayam is dark. There is some mistake in the picture which makes it unreliable for comparisons. NASA dhaivam onnumallalo?

[mohammedirshad06]

del
.

[psanthosh]

Originally Posted by mohammedirshad06

del
.

Thanks.. otherwise all need to spend time on reading another discussion thread on this sky light photo released by NASA a week ago. Even NASA might have forgot that image by this time.

[PPJ]

In the mean time

One of our old member has came back and very active now. Elarkum best of luck.