Feature Identification » Identifying Surface Features » Water Bodies

Bodies of water like oceans, large lakes, and even wide rivers are easy to see on most satellite products. The main exception is WV imagery, which cannot see to the surface.

Water temperatures do not change dramatically during the diurnal heating cycle like land surface temperatures do. Therefore, water is typically cooler than the surrounding land surfaces during daytime and has a whiter appearance in the infrared images below.

EUMETSAT infrared over southern Africa, 1200 UTC 26 Jun 2016

At night, when land surfaces cool rapidly, their temperatures may go below that of water. This means that water will have a warmer brightness temperature and appear darker than the surrounding land.

EUMETSAT infrared over southern Africa, 0000 UTC 26 Jun 2016

Occasionally, water and land temperatures are so similar that water bodies are completely camouflaged. That’s the case with Lake Malawi in the image below, which we can barely detect. However, in the previous image, you can find Lake Malawi quite readily on the border between Malawi, Tanzania, and Mozambique.

EUMETSAT infrared over southern Africa, 0600 UTC 26 Jun 2016

Let’s take a look at how water bodies appear in RGBs compared to VIS and IR imagery. In the slider interactions below, the IR image always displays first. Select the other images to compare them to it.

Here are images from mid-day.

Left Side Image
IR
Right Side Image
left side product right side product

Now look at midnight scenes.

Left Side Image
IR
Right Side Image
left side product right side product

Finally, let’s look at the 0600Z imagery. At this time, the sun has recently risen which rapidly changes the colors in some of the imagery. In some cases the water bodies remain warmer/colder than the surroundings, while in others, the land and water become nearly indistinguishable.

Left Side Image
IR
Right Side Image
left side product right side product

Question

For each product listed below, indicate the colour you would expect water to be during each time of the day. (Use the above sliders to help you answer these questions)

During the day:

a) Severe Convection
b) Dust
c) Natural Colour
d) Night Microphysics

During the night:

a) Severe Convection
b) Dust
c) Natural Colour
d) Night Microphysics
Please make a selection.

If you haven’t already done so, verify your answers with the imagery above. Use the 12Z for the daytime questions and the 00Z for the nighttime questions.

Please make a selection.