  The Extreme Universe Space Observatory-Super Pressure Balloon (EUSO-SPB1) is
a pathfinder of the JEM-EUSO program, which aims to observe Ultra High Energy
Cosmic Rays (UHECRs) from near-space. It was launched from Wanaka (New Zealand)
on April 25, 2017 UTC and was terminated after twelve days of flight in the
South Pacific Ocean. A good knowledge of the atmospheric conditions and cloud
properties, such as the Cloud Top Height (CTH), is fundamental to correctly
reconstruct the energy and geometry of air showers produced by cosmic rays
passing through the atmosphere. One of the methods used to retrieve the CTH is
based on Numerical Weather Prediction models. In this work, we consider in
particular the Weather Research and Forecasting (WRF) model. A first model test
is made on the WRF parametrizations for elementary processes, applying a
top-bottom directed algorithm based on two quantities: cloud fraction and
optical depth. The validated procedure is then applied to the SPB1 trajectory,
retrieving the CTH every ten minutes for the days of the flight. A comparison
is made with the analyzed data taken from MODerate resolution Imaging
Spectroradiometer (MODIS) satellite images, once per day, to understand the
reliability of the method. Another way to retrieve the CTH is the so-called
radiative method, that allows to calculate the Cloud Top Temperature (CTT). A
vertical temperature profile is needed to transform the CTT into CTH. When
radiosoundings are not available, WRF can provide vertical temperature
profiles. The conversion from the CTT to the CTH is then made.
