• The satellite image shows separate cloud sheets, which vary in size from relatively small (around 10 000 - 50 000 km²) areas to extensive, synoptic scale features (up to and above 1 000 000 km²). In geostationary satellite imagery (especially in northern latitudes) Stratocumulus (hereby referred as Sc) Sheets have a relatively homogeneous appearance both in VIS and IR channels. Polar orbiting satellites reveal a great deal of substructures (cellular-, roll- or ripple-like details) in the texture of the Sc Sheets.
• In the VIS image (Ch1 or Ch2 images when applied to polar orbiting satellites) the grey shades of the Sc Sheet are usually white or grey depending on the thickness of the cloud sheet and sun elevation. The cellular-like pattern is common for Sc Sheets (in contrast to Fog or Stratus shields, which have a flatter appearance). In VIS images the clouds are of varying brightness indicating varying thickness of the cloud layer.
• In the IR image (Ch4 or Ch5 when applied to polar orbiting satellites) the grey shades of the cloud shield are usually grey or dark grey indicating relatively low (warm) cloud tops. The appearance of Sc Sheets is smoother in IR than in VIS, which is due to the uniform cloud top height. The detection of cloud sheets using the IR image can sometimes be difficult if temperature difference between cloud tops and surface is small. Temperature difference can even be reversed, that is, cloud tops can show warmer temperature than surrounding cloud-free surface areas causing a black appearance of the cloud. This is especially the case in high latitudes during the cold season, when radiative cooling of surfaces beneath cloud-free areas can be remarkably strong.
• In the WV channel the Sc Sheets are normally invisible. This is due to the limited vertical extent of Sc Sheets (usually only up to 1 - 2 km). WV imagery can, however, be indirectly useful: the horizontal advection of upper-level moist air (although without associated clouds) over the Sc Sheet may change the radiation balance of clouds, further leading to dissolving of the cloud sheet.
• Combination images, such as the daytime RGB image (channels 1,2 and 4) of polar orbiting satellites, greatly help in identifying low level Sc Sheets. In RGB-124 imagery Sc Sheets are seen as yellowish or yellowish-white cloud masses. In nighttime RGB images (using channels 3, 4 and 5) Sc Sheets have a dark red appearance.
• The edges of Sc Sheets can be very sharp, but normally they are more ragged, especially when the cloud sheet starts to break up. The dissolving of even an extensive cloud sheet can happen very quickly (in hours), when radiative or turbulent mixing processes become favourable. Thinness of the Sc layer helps in rapid dissolving of the cloud layer over land. The Sc Sheet can also have a different appearance during the day than during the night. The underlying surface also has an effect on the appearance of cloud sheet; for example, over the ocean the clouds have a cellular-like appearance arising from spatially organized convection.

The images show extensive Sc Sheetss over eastern and northern Finland.
There is also some mid-level cloudiness, which can be seen as colder patches in the IR image (right image top). The appearance of the Sc Sheets in the IR image is quite homogeneous indicating uniform cloud top temperatures.
The VIS image (left image top) shows more details. The brightness of the clouds varies remarkably. A cellular appearance is apparent in the VIS image, which is a typical feature for daytime stratocumulus over land.
In the RGB image (left image bottom) the stratocumulus is clearly yellowish in colour. The detection of small-scale features, such as the Cloud Streets in southern Finland, is also easy with the help of this kind of imagery.
The sounding of Jokioinen (denoted with J in RGB image) (right image bottom) shows the vertical structure of the atmosphere within the stratocumulus area. The thickness of the Sc clouds is approximately 300 metres. The temperature inversion is quite weak at this stage. The early morning images of 13 April 1998 show further development of the cloud sheet. Separate Sc Sheets can be found over southern Finland, Karelia and Estonia. Cloud tops have now a much flatter appearance compared to the daytime images, and cellular features have totally vanished during the night. The edges of the Sc Sheet are also quite sharp.
The corresponding sounding for Jokioinen at 00.00 UTC is also shown (bottom right image). It shows that stratocumulus has become quite thin, with its vertical extent only some 100 - 300 metres, and temperature inversion just above the cloud sheet has increased significantly. Dry subsiding air above the Sc Sheet is destroying the sheet, which totally dissolves within only a few hours.

Appearance in AVHRR imagery

• AVHRR imagery can reveal some detailed structure of stratocumulus clouds. Texture within the cloud top, e.g. cellular patterns, waves and ripples, etc., are easy to detect with combined images NOAA 124 and NOAA 345, however, even the individual channels show these small-scale patterns quite well, especially at low sun angles (shadows enhance contrasts between cloud elements).
• Cloud streets within stratocumulus are also often easy to detect in AVHRR imagery.
• During daytime combined image NOAA 124 shows Sc Sheets in yellow or light yellow colours. This combination sometimes also helps in differentiating between stratus and stratocumulus, as stratus clouds are deeper yellow, even brownish yellow (compare Stratus and Fog - Cloud strusture in satellite images ).
• During nighttime the difficulties in differentiation between cloudy and cloud-free areas become evident, if the cloud-top temperatures are about the same as the surface temperature on surrounding cloud-free regions. In nighttime NOAA 345 combined images Sc Sheets have a dark red appearance. Differences between the colour in Stratus and stratocumulus are small, but stratocumulus tops, being warmer, have a slightly lighter red appearance compared to stratus clouds.
• Diurnal variations in cloud top structure can easily be seen in AVHRR imagery (see previous example). This applies mostly to summertime cases; during wintertime continental stratocumulus tops have a flatter appearance, both day and night.

The satellite image shows an extensive Sc Sheet over Northern Scandinavia. Due to low sun elevation the varying texture within the cloud top is easily seen in visible 0,9 µm (channel 2) image. Combined image NOAA 124 shows the Sc Sheet in a light yellow colour, while combined image NOAA 345 shows the cloud sheet in light reddish colours. The night-time NOAA 345 image (bottom left) is included for comparison.