The ‘Clouds’ layer in Google Earth

A GEB reader recently remarked that the Google Earth Clouds layer (a sub layer of the Weather layer) appears to have fewer clouds than it should when compared to the ‘Radar’ layer that often shows rain and storms in apparently cloud free areas.

The first thing to know about the Clouds layer is that it is not an optical photo of the clouds as they are seen from space. If we look at the images from a weather satellite such as Himawari 8, that we have looked at in the past, we can immediately see one of the problems that would arise from purely optical images. Approximately half the Earth is in darkness at any given time.


Left: Google Earth Cloud layer. Right: Image from Himawari weather satellite.

Weather satellites have a range of sensors that can detect clouds even in darkness. They make a map of the clouds that is then converted into an image with white where the clouds are that is then used in Google Earth. However, they appear to focus only on thick clouds, which results in an image showing a lot less clouds than can be seen in an typical photo from a weather satellite.

The Weather layer has an Information layer that includes the option to download animations of the Clouds and Radar layers. It also tells us that the data for the Clouds layer comes from the Naval Research Laboratory (NRL) Marine Meteorology Division. We had a look around their website but were unable to determine exactly which satellites are used for the Google Earth Cloud layer or anything about the process used. We think the data may come from MODIS (or Moderate Resolution Imaging Spectroradiometer) an instrument found on the Terra and Aqua NASA satellites. Learn more about them here. We also found this highly technical article about the algorithms used to collect cloud data and it is clearly a complicated process.

If any of our readers knows more about where the Google Earth Cloud layer comes from and how it is processed please let us know in the comments.

About Timothy Whitehead

Timothy has been using Google Earth since 2004 when it was still called Keyhole before it was renamed Google Earth in 2005 and has been a huge fan ever since. He is a programmer working for Red Wing Aerobatx and lives in Cape Town, South Africa.






PLEASE NOTE: Google Earth Blog is no longer writing regular posts. As a result, we are not accepting new comments or questions about Google Earth. If you have a question, use the official Google Earth and Maps Forums or the Google Earth Community Forums.

Comments

  1. there was a kml few years back, that overlaid Aqua and Terra daily images in Google Earth. later it stopped working. is there any that works?

    • I would be great to have a 3D clouds layer in Google Earth like e.g. in MS Flight Simulator, which is based on METAR data from airports.

  2. I don’t know from where exactly Google gets their cloud imagery, but suffice it to say, meteorological images of cloud layers are rarely based only on visible wavelengths (because, as you say, half of the time half of the earth is dark). In fact the Google images (to me) very much look like infrared wavelengths, and those do look significantly different than visible. It also wouldn’t surprise me if there was some other data mixed in (or mixed out…) that satellites also gather, such as moisture, fog, precipitation, water vapor, etc. – not everything that’s white in the sky to the human eye is technically a “cloud”.



PLEASE NOTE: Google Earth Blog is no longer writing regular posts. As a result, we are not accepting new comments or questions about Google Earth. If you have a question, use the official Google Earth and Maps Forums or the Google Earth Community Forums.