|
|
Thunderstorm as a hazardous atmospheric phenomenon and possibilities of its forecasting
Valachová, Michaela ; Žák, Michal (advisor) ; Řezáčová, Daniela (referee)
In the presented work we deal with the possibility of thunderstorm forecasting. Convective storms are probably the most serious consequences of severe weather in the Czech Republic. Even through the big progress in numerical weather prediction methods, the forecast of their occurrence and intensity estimation remains very difficult when issuing warning information for the given area. Knowledge of nowadays possibilities of strong convection forecasting is included. To study the success of the thunderstorm prediction we chose the set of thunderstorm events with significant convective phenomena identified in the Czech Republic. Data from numerical weather prediction models, aerological stations and remote sensing of Earth were used. These selected cases were assessed with respect to practical using in the Integrated Warning System in the Czech Hydrometeorological Institute.
|
|
|
Selected hazard weather phenomena and their impact on various types of aircrafts
Indráková, Radka ; Keder, Josef (advisor) ; Žák, Michal (referee)
Despite of technical progress of aircrafts in last decades, hazard weather phenomena such as icing, turbulence or vertical wind shear still represent significant risk factor for all aircraft categories, especially during the approach and landing flight phases. The goals of diploma theses are to summarise present knowledge on influence of these phenomena on various categories of contemporary aircrafts, to describe possibilities of prediction of these phenomena and to outline an application of LAM NWP models outputs to this purpose. An assessment of such forecast performance comprises a part of thesis as well.
|
|
| |
|
|
Validation of atmosphere prediction model in meso-scale
Mejstřík, Tomáš ; Žák, Michal (advisor) ; Řezáčová, Daniela (referee)
In this thesis, we are aimed at various physical principles of convective parametrization. First, traditional parametrization schemes are described. This schemes are based on hypothesis of quasi-equilibrium between large-scale processes and convective activity and suggestion about negligible mesh fraction of convection in grid-box. But, passing to resolution in the range below 10 km, the deep convection si partly subgrid, partly resolved. A new generation of prediction with high horizontal resolution is now introduced. This model has new prognostic convective scheme with new description of interaction between convective mass transport and microphysical computation of clouds and precipitation. A prognostic scheme has been used for the vertical velocity of udraft and downdraft and more elaborate microphysics, include effect of autoconversion, evaporation and sedimentation of precipitation. These models are expected to forecast many atmospheric events much more precisely (e.g. strong convection). Validation of model in experiments at different resolutions is the main task of this work. Comparsion of new developed model with model currently used, sensitivity study of new components, are presented.
|
|
|
Specifics of climate of Prague and its relation to air pollution
Hošek, Jiří ; Sládek, Ivan (advisor) ; Žák, Michal (referee) ; Prošek, Pavel (referee)
I l::r,iduction -: _-::r: ;.inrate is an important part of life of rising number of people and it is* .." ř: :-': :-: ..\:lh increasing intensiý. Large cities have their specific mesoclímate that is.--l'.--.: :'.::ll1' by higher air temperature and lower humidiý. The reason is_:- '- .i..-. :=lermeab'e surťace, for which there is rapid runoff of precipitation, and:. .: : -::=-::-s. rvhich causes the ciý to absorb heat during the day and generate it during* : !-- l:: ::ler characteristics ofthe urban climate -.Ť: - iš::]:-\ of heat, increased surface roughness #;:Tffi:":''::".n1:I1*::' ř -'! .: :::]'.:ence on the temperafure and wind Íield over the urban area. --: .: of this work was to assess statisticar characteristics of wind field and urbanj :- :-: :::rerature on the area ofprague and its relation the air potution. The first step'- :ii-':::'-n and verification ofsurface wind field over the area ofprague usrng a::-.*:1 :-.ťel. Furthermore, other variables were calculated such as mixing length and: L' "' -;tor' rvhich are connected to the air pollution. The wind field calculation was' -.: :i Lisessm.nt of heat budget of built-up urban suďace. For that purpose' a. :j::.]:: s;heme rvas applied, which is capable to treat very complex suďace of the city. In:; ::' :::1 0f the work' the relation between...
|
|
| |
|
| |
|
| |
|
|
Study of the properties of cement concrete at high temperatures
Žák, Michal ; Sitek,, Libor (referee) ; Bodnárová, Lenka (advisor)
This diploma thesis is focused on behavior of cement concrete at high temperatures. The theoretical part describes processes, which take place in concrete at thermal loading and effect of this thermal load to mechanical and physical properties of concrete. Also there was described recommendation for testing physical and mechanical of concrete at high temperatures according to RILEM TC. In experimental part mixes were made with greywacke aggregate, amphibolite aggregate and with the addition of polypropylene fibers or cellulose fibers. In these mixes was determined the effect of high temperatures on the density of concrete, compressive strength of concrete and thermal strain of concrete. Further there was tested addition of 2 kg/m3 polypropylene fibers to concrete with basalt aggregate and siliceous aggregate and influence of these fibers to density of concrete, compressive strength of concrete and dynamic modulus of elasticity.
|
|
| |
guest ::
RSS feed.