Description: The atmospheric space from 11° N to 5° S along the Somali-coast of East-Africa over the western part of the Arabian Sea has been investigated making use of the aerological measurements, gained during the International Indian Ocean Expedition (IIOE) 1964/65. On the basis of the analyses obtained, an attempt is made to compute a heat budget for this space. In particular the following components have been taken into account: the net-radiation flux in the atmosphere (GN), the turbulent flux of sensible heat (Qs) and of latent heat (QL) from ocean to the atmosphere above, the potential (P), the sensible (I) and the latent energy (E). The vertical velocity component (ω) has been carefully determined making use of the adiabatic method but considering nonadiabatic effects of various kind lateron. From the vertical divergence of the net-radiation flux the cooling by long wave radiation was computed. Maximum effect of this process was obtained in the monsoon inversion (-5.4°C/day). Above the tropical tropopause the atmosphere shows maximum warming of 1.8°C/day. The intensity of the turbulent flux of sensible and latent heat is mainly determined by the windfield and by the local differences in the watertemperature. Maximum values are for Qs = 12·10-4 cal cm2 sec-1 and for QL = 140·10-4 cal cm2 sec-1 (Bowen-ratio R = Qs/QL = 8.5%, mostly not more than 4-5%). The computation of the vertical velocity rests besides the thermodynamic method (adiabatic) on a consideration of various non-adiabatic effects such as radiation, flux of sensible and latent heat. The following distribution has been obtained: Below the monsoon inversion a rising motion (maximum -30·10-4 mb/sec ≈ +2.8 cm/sec) and above a sinking motion (maximum +20·10-4 mb/sec ≈ -3.4 cm/sec) upwards to the tropical tropopause (near 90 mb). Above the tropopause weak rising motion (-2·10-4 mb/sec ≈ +1.3 cm/sec) was obtained. An attempt to compute various terms (in total 7) of the heat budget equation shows, that horizontal advection of various energy forms are only of importance in the monsoon layer (below the inversion) and above the tropical tropopause. In all height-intervalls considered the vertical advektion of the energy forms is dominant. The results of the budget-computation are presented in graphical form.