In this study, four and a half months of ceilometer data from Östergarnsholm are used to analyze cloud related to processes in the boundary layer. Measurements are divided into two categories, which are defined by wind direction: a continental and a marine sector. The results show that there are significant differences in the height of the lowest cloud bases detected for the two sectors, where cloud base heights are lower for the marine wind sector during unstable and neutral conditions. The ceilometer’s ability to detect several cloud base heights simultaneously is utilized to test whether a double layer structure (DLS) can be detected. The results of this particular analysis are inconclusive as to whether a DLS has been observed or not. Detected cloud base heights differ greatly from heights suggested by the lifting condensation level (LCL). A new empirical formula for lowest cloud base height is then derived using the measurements. The Ceilometer’s estimations of sky cover are assessed to be of reasonable quality. This is suggested by computed high correlation with incoming shortwave radiation at noon for three months.  However, histograms of cloud cover measurements suggest that the ceilometer tends to probably either overestimate or underestimate cloud cover.  Large differences in cloud cover were observed for the two wind sectors during unstable conditions. For the months of July and August, a diurnal cycle in cloud cover for the continental wind sector was observed which suggest the presence of Stratocumulus. Measurements performed during upwelling conditions closely resemble those of the marine wind sector performed during stable conditions.

LONG-TERM CHANGES IN CLOUDINESS AND SUNSHINE DURATION IN EUROPE Abstract The aim of this paper is to study long-term changes of two climatological parameters known as sunshine duration (SD) and cloudiness (CC) using several stations data located in Europe in the period 1965 - 2016. This paper is devided into two main parts. First part is paying attention to the literary research, which firstly introduce the chosen climatical variables (SD and CC) and then introduce the issue of the already known long term changes of this variables. Second part of this work is based on practical research. This paper uses a statistical linear regression to find out the seasonal and annual trends in sunshine duration and cloudiness. Data series were obtained from database ECA&D in total from 48 european climatic stations. Klíčová slova: cloud cover, sunshine duration, climate change, trends, Europe

The Eppley Precision Pyranometer (PSP) is a radiometer used in networks around the world to measure downwelling and upwelling diffuse and total hemispherical broadband solar irradiances. PSP's present an offset in the signal, called thermal offset, produced by a radiation heat exchange between the glass dome, which defines the spectral throughput and the detector. This offset can reach up to 15\% of the total value of the signal when measuring diffuse irradiance under clear sky conditions. The thermal offset is characterized by monitoring the temperature gradient between the dome and detector using thermistors at key locations. The temperatures are acquired by using thermistors. Relationships between the thermal offset and the temperature gradient are established using nighttime data and subsequently used to estimate the offset during daytime. To correct historical data the thermal offset is related to other variables such as the output of a Precision Infrared Pyrgeometer (PIR) or the fraction of cloud cover in the sky. The use of thermistors is a very reliable method to estimate and correct the thermal offset. The relationships between the offset and the IR output and between the offset and the cloud cover fraction provide good estimates of the thermal offset in historical data sets, reducing it 60% to 100% depending on the instrument and the relationship used. / Master of Science

Topic of this master thesis is to examine whether weather related mood changes are in correlation with price of stocks. Thesis focuses on middle Europe stock market indexes PX, SAX, ATX and DAX. Research is based on relationship between daily cloud cover and development of the indexes form 1995 to 2012. It also focuses on comparison of several different models, especially models of seemingly unrelated regressions. It shows that indexes PX and ATX are significantly negatively correlated with local cloud cover. Use of seemingly unrelated regressions offers slightly better results. The relation between cloud cover and stock indexes is not strong enough to be used for weather based speculations

One major challenge in representing the state of the atmosphere through weather forecast models, is the parametrization of sub-grid clouds. At every vertical column of grid cells within a weather forecast model, the fractional cloud cover is assumed to overlap according to a prescribed Cloud Overlap Assumption (COA). Since the total cloud cover is used in radiation schemes, the choice of COA affects e.g. radiative fluxes. High-quality weather forecasts is important for many aspects of the society, thus, the analysis of cloud parametrizations is significant. In this study, COAs for the HIRLAM ALADIN Research on mesoscale Modelling for NWP In Euromed (HARMONIE) - Application of Research to Operations at Mesoscale (AROME) model were investigated for two time-periods. Moreover, validation methods of cloud cover for HARMONIE-AROME were analyzed due to uncertainties in cloud observations. Both satellite data derived from geostationary Meteosat Second Generation (MSG) satellite and synoptic ground based observations were used to validate cloud cover in this project. It was found that HARMONIE-AROME underestimates the cloud cover during summer. Therefore, the random (RAN) COA is the preferred COA to use during time periods of mainly convective cloud processes. During the tested winter period, which is assumed to have most clouds of the stratiform type, the results regarding optimal COA were not certain. However, it was concluded that HARMONIE-AROME overestimates the cloud cover during winter, for in which case the maximum-random (MRN) COA is recommended to use. The comparative analysis of cloud cover as obtained from the COAs against observed cloud cover, was shown sensitive to the methods used to the observational data. Using a model grid of 25 km instead of 2.5 km when comparing synoptic observations to modelled cloud cover, the errors were reduced. When using binary satellite data, it was concluded that a 5x5 smoothing algorithm was the most appropriate to use since this averaging of several pixels are sufficient to represent sub-grid clouds.

Approved for public release, distribution is unlimited / The Monterey Bay sea breeze varies because of the influence of features such as inversions, clouds, synopticscale flow, and topography. The sea breeze is important because it impacts fire weather, air pollution, agriculture, and aviation operations, among other things. Analyses are conducted using a multi-quadric based program, which incorporates aircraft data, surface observations, and profiler data, to investigate the Monterey Bay sea breeze during 01-31 August 2003. Factors including inversions, cloud cover, amount of heating, distribution of heating, synoptic-scale flow, and topography are studied to determine their influence on the sea breeze. Six days are selected that best illustrate the factors that influence the structure of the Monterey Bay sea breeze. Results show that offs hore flow weakened the strength of the sea breeze and decreased the depth. A cooling trend in surface temperatures at the end of August also weakened the strength of the sea breezes and decreased the depth. Clouds are present during this period, which influenced the amount of heating, and consequently, the sea breeze response. The presence of a marine layer weakened the thermal gradient that in turn, weakened the sea breeze circulation. / Lieutenant Junior Grade, United States Naval Reserve

Nachhaltige Architektur erfordert neue Bauformen, innovative Konstruktionen und die Verwendung neuartiger Baumaterialien. Zur Abschätzung des Risikos von feuchtebedingten Schäden finden Programme der hygrothermischen Bauteilsimulation Anwendung. Bei der Entwicklung solcher Simulationsprogramme spielt die korrekte Modellierung der Klimarandbedingungen eine entscheidende Rolle. Beim Übergang von der kurzwelligen horizontalen Strahlungsstromdichte auf die kurzwellige Strahlungsstromdichte eines beliebigen Bauteils müssen Himmelsrichtung der Flächennormalen und die Neigung des Bauteils zum Ausschluss von Eigenverschattung berücksichtigt werden. Das dargestellte integrale Modell erlaubt die Berechnung und Programmierung in einem hygrothermischen Simulationsprogramm. Für den Fall, dass nur Messwerte der globalen Strahlungsstromdichte zur Verfügung stehen, können die direkten und diffusen Anteile mithilfe geeigneter Modelle mit einer sehr guten Genauigkeit berechnet werden. Zur Berechnung der langwelligen Strahlungsbilanz eines Bauteils stehen nur selten jene Klimaparameter zur Verfügung, mit denen die atmosphärische langwellige Strahlungsflussdichte analytisch bestimmt werden kann, weshalb semi-empirische Modelle Anwendung finden müssen. Die langwellige Ausstrahlung der Atmosphäre kann mithilfe von bodennaher Lufttemperatur und Luftfeuchte sowie zweier Bedeckungsgrad-Indizes berechnet werden, welche die langwelligen Strahlungseigenschaften der Atmosphäre auf der Basis der vorhandenen kurzwelligen Strahlungsstromdichten beschreiben. Damit wird erstmals ein umfassendes Modell für die langwellige Strahlungsbilanz vorgelegt, welches alle Möglichkeiten der Datenverfügbarkeit berücksichtigt. Die Berechnung der Schlagregenstromdichte auf ein Bauteil kann mit den meisten vorliegenden semi-empirischen Modellen nur sehr ungenau erfolgen. Andere Verfahren, wie z.B. CFD-Simulationen, kommen wegen des beträchtlichen Aufwands meist nicht in Frage. Das bislang einzige vorliegende umfassende validierte semi-empirische Modell von Blocken kann durch die Berücksichtigung der mesoklimatischen Verhältnisse in seiner Genauigkeit verbessert werden. / Sustainable architecture requires new building design, innovative constructions and the use of newly developed building materials. In order to determine the risk of moisture-related damages, computer programs for hygrothermal building part simulation are being used. If one develops such a simulation program, correct modelling of climatic boundary conditions plays an important role. When calculating the shortwave solar radiation flux density at an arbitrary building part on the basis of the shortwave solar radiation flux density on the horizontal surface, one must take into consideration the orientation and the inclination of the building part in order to preclude self-shading. The presented integral model allows the calculation and the programming in a hygrothermal simulation program. If only measured values of global radiation flux density are available, direct and diffuse parts can be determined very precisely by means of validated models. When calculating the longwave radiation balance on a building part, the needed values for the correct determination of atmospheric longwave radiation are hardly available. That’s why semi-empirical models will be applied. The longwave radiation flux density of the atmosphere can be determined on the basis of near-ground temperature and relative humidity and two cloud cover indices, which describe the longwave irradiative properties of the atmosphere by means of available shortwave radiation flux densities. Therewith, firstly an integral model is being presented in order to determine longwave radiation balance, which considers all possibilities of data availability. Most models for determination of driving rain load work with very bad accuracy. Other methods such as computational fluid dynamics (CFD) are not possible for hygrothermal building part simulations because of the huge effort. The only fully validated semi-empirical model by Blocken can be improved, if meso-climatic boundary conditions are taken into consideration.

Representations of Boundary Layer Cloudiness and Surface Wind Probability Distributions in Subtropical Marine Stratus and Stratocumulus Regions Yanping He 153 pages Directed by Dr. Robert E. Dickinson A simple low cloud cover scheme is developed for the subtropical marine stratus and stratocumulus (MSC) regions. It is based on a modified CIN concept named the Lower Troposphere Available Dry Inhibition Energy (ADIN). The e-folder time for the local change of ADIN is found to be approximately 6 to 7 hours. On monthly and longer timescales, local productions of ADIN are balanced by local destructions of ADIN within lower troposphere. Dynamical transport of environmental dry static energy and surface evaporation lead to the variations of cloud top radiative cooling, which is a linear function of low cloud cover. Data analysis suggests that total ADIN dynamical transport plays the most important role in determining the seasonal variations and spatial variations of low cloud amounts¡£ The new scheme produces realistic seasonal and spatial variations of both EECRA ship observation and satellite observations in all MSC regions. It explains 25% more covariance than that using Klein-Hartmann (KH) scheme for monthly ISCCP low cloud amount near the Peruvian and Canarian region during the period from 1985 to 1997£¬it better represents the relationship between ENSO index and low cloud cover variations near the Peruvian region. When implemented into NCAR CAM3.1, it systematically reduces the model biases in the summertime spatial variations of low cloud amount and downward solar radiation in the Peruvian, California, and Canarian regions. Model simulated summertime cloud liquid water path, large scale precipitation, and surface fluxes are also significantly changed. A single predictor named Lower troposphere available thermal inhibition energy (ATIN) is also shown to be more skillful than the lower tropospheric stability in diagnosing low cloud stratiform clouds in the monthly and seasonal timescales. On synoptic timescale, dynamical transport of available dry inhibition energy and surface evaporation are better correlated with marine low cloud amount variations than ATIN and lower troposphere stability. The influence of boundary layer clouds, ocean surface SST, and large scale divergence on the stochastic dynamics of local ocean surface winds are addressed using QuikSCAT and AIRS satellite observations and a simple conceptual model in the southeast Pacific. The ocean surface pressure gradient depends on both the boundary layer height and temperature inversion strength. Marine boundary clouds are diagnosed using the cloud cover scheme developed in Chapter 2. The model successfully reproduces the observed mean state, the standard deviation, and skewness of local surface wind speeds in the southeast Pacific.

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From the Proceedings of the 1978 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 14-15, 1978, Flagstaff, Arizona / In an effort to improve the methods of forecasting the amount and timing of snowmelt, a primary source of water in Arizona, significant regression equations are developed over a selected measurement period to relate global, direct, and diffuse solar radiation to: (1) the cloud-cover of specific cloud genera, (2) the hour before or after solar noon, and (3) the potential solar radiation. Three regression equations are derived from cloud-cover imagery and solar radiation data collected from two sites in Arizona 's Ponderosa pine forests, Schnebly Hill, and Alpine, in the hope that regression models will be useful in the simulation of snowpack dynamics.