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The cloudiness represents one of the basic climate elements. It plays an important role in the global energy and water cycle, dominates the planetary albedo and takes part in many climate feedback processes. Its traditional man-made observation provides usually high-quality data. But it is partly influenced by the observer capabilities to see various cloud layers if lower layers are presented hiding the higher ones. Of course, the quality usually differs between observations made during day and by night. On the other side, manual observation is quite expensive if you want to have uninterrupted long-time series of high density network over large area. Here, you can benefit from satellite data that provide more complex view of the cloudiness above given area and definitely are less expensive. On the other hand, satellite data sustain some problems regarding its limited horizontal resolution that can lead to fact that some details can be hidden or not properly recognized. Some satellite information is provided on daily or larger time frequency only and this can be sometimes problem, too. Nowadays, due to better geometric resolution and more exact calibration, more and more applications for satellite data in climatology can be found and it has also sufficient length to be used in climate analysis as noted by Schulz1. In this paper we focus on cloudiness satellite data usage for the climatology purposes in the Czech Republic area. For this reason, data provided by Satellite Application Facility on Climate Monitoring (CM-SAF) supported by the European Organization for the Exploitation of Meteorological Satellites (EUMETSAT) have been used. CM-SAF data products are distinguished between operational monitoring products and retrospectively produced data sets. We have used products, so far. Studies describing validation of cloud products or cloud detection schemes with synoptic or other kinds of data can be found in literature (e.g. Reuter2, Karlsson3, 4). The basic motivation for this work was to find answer whether it is possible to replace surface cloud observation by satellite measurements and/or in which case or under which circumstances. For this reason, features of operatively available daily products of CFC (Cloud Fractional Cover) and CTY (Cloud Type) were analyzed in the area of the Czech Republic territory.
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