According to the peculiarities of climatic conditions of Lithuania the change in Chebil's model was made. For the first time the rain rate values for 13 localities in Lithuania have been calculated using this model. This data has shown that the definition of Rain Zone E does not describe the Lithuanian climatic conditions. The values of rain attenuation have been calculated as well. The Flavin's relationship for calculations of rain attenuation was used. The dependences of rain attenuation on the frequency for both locations of Ukmergė and Laukuva have been calculated. A review of the results on the rain rate and rain attenuation can be entered into total attenuation prediction or system-planning tools.

The peculiarities of the climatic conditions in the Baltic Sea Region are reviewed. According to the values of rain rates measured in the Lithuanian Weather Stations with the 10minute's integration time, a relation between the rain rate and the annual precipitation has been derived. The model for one-minute rain rate calculation on the months starting from May up to September in Lithuania has been presented. The values of the electromagnetic waves attenuation due to the rain have been determined. The cloud attenuation has been computed by using the meteorological data measured at the ground level. The semi empirical method has been used. The values of the specific attenuation under conditions of cloud cover have been determined.

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The values of the rain rates were calculated by using a new revised model. The obtained values of rain rates were compared with the ITU-R (International Telecommunication Union -Radio Regulations) value ascribed to Lithuania and with ones measured in the Lithuanian Weather Stations. The dependences of rain attenuation on the frequency for three locations of Biržai, Vilnius, and Kaunas have been calculated by using the values of the rain rates R obtained here and the ITU-R value. The dependence of rain attenuation on the frequency for Biržai has been calculated by using the value of rain rate obtained using Chebil's model as well. The suspicion that ITU-R value of R 0.01% is too low, described in previous paper, has been confirmed by the data presented here.

Yearly, seasonal and daily variations of radio refractivity have been analyzed. The method proposed in the recommendation of International Telecommunication Union ITU has been used. The local meteorological data have been used in calculation of radio refractivity. The highest values of the radio refractivity have been observed in Klaipėda (in Seacoast) in the year 2009. In July, the values of the radio refractivity were highest in all localities investigated here and over all the time of the day in the year 2009. In the continental part of Lithuania (in Vilnius and Kaunas), analysis of radio refractivity has been made by using the meteorological data of longer period (starting from April 2005 up to July 2010). Five-year meteorological data collected in February, April, July and October have been used. It was obtained that the values of refractivity in the year 2010 are much higher than ones obtained in all the years of the period investigated here.