Assessment of the Spatio-Temporal Trends of Annual Extreme Temperature Indices over Tanzania during the Period of 1982-2022

Extreme weather and climatic phenomena, such as heatwaves, cold waves, floods and droughts, are expected to become more common and have a significant impact on ecosystems, biodiversity, and society. Devastating disasters are mostly caused by record-breaking extreme events, which are becoming more frequent throughout the world, including Tanzania. A clear global signal of an increase in warm days and nights and a decrease in cold days and nights has been observed. The present study assessed the trends of annual extreme temperature indices during the period of 1982 to 2022 from 29 meteorological stations in which the daily minimum and maximum data were obtained from NASA/POWER. The Mann-Kendall and Sen slope estimator were employed for trend analysis calculation over the study area. The analyzed data have indicated for the most parts, the country has an increase in warm days and nights, extreme warm days and nights and a decrease in cold days and nights, extreme cold days and nights. It has been disclosed that the number of warm nights and days is on the rise, with the number of warm nights trending significantly faster than the number of warm days. The percentile-based extreme temperature indices exhibited more noticeable changes than the absolute extreme temperature indices. Specifically, 66% and 97% of stations demonstrated positive increasing trends in warm days (TX90p) and nights (TN90p), respectively. Conversely, the cold indices demonstrated 41% and 97% negative decreasing trends in TX10p and TN10p, respectively. The results are seemingly consistent with the observed temperature extreme trends in various parts of the world as indicated in IPCC reports.

The Effective Temperature and the Absolute Magnitude of the Stars

The theoretical framework developed by A.S. Eddington for the study of the inner structure and stability of the stars has been modified by the author and used in this work to show that knowing the effective temperature and the absolute magnitude, the basic parameters of any gaseous star can be calculated. On the other hand, a possible theoretical explanation of the Hertzsprung-Russel Diagram is presented.

Two innovative equivalent statements of the third law of thermodynamics

It is found from textbooks and literature that there are three different statements for the third law of thermodynamics,i.e., the Nernst theorem, the unattainability statement of absolute zero temperature, and the heat capacity statement. It is pointed out that such three statements correspond to three thermodynamic parameters, which are, respectively, the entropy,temperature, and heat capacity, and can be obtained by extrapolating the experimental results of different parameters at ultralow temperatures to absolute zero. It is expounded that because there is no need for additional assumptions in the derivation of the Nernst equation, the Nernst theorem should be renamed as the Nernst statement. Moreover, it is proved that both the Nernst statement and the heat capacity statement are mutually deducible and equivalent, while the unattainability of absolute zero temperature is only a corollary of the Nernst statement or the heat capacity statement so that it is unsuitably referred to as one statement of the third law of thermodynamics. The conclusion is that the Nernst statement and the heat capacity statement are two equivalent statements of the third law of thermodynamics.

Precipitation kinetics of complex precipitate in multicomponent systems

A kinetic model based on the classical nucleation and growth theory has been proposed to predict the precipitation behavior of complex precipitate. The method for calculating absolute solution temperature, which is an important guidance for determining solution treatment temperature, is also proposed based on thermodynamic model. In the model, nucleation of the second phase is assumed to be controlled by the effective diffusion, which involves the bulk diffusion and dislocation pipe diffusion, and growth is controlled by the bulk diffusion of forming elements. The interfacial energy of complex precipitate is calculated by the linear interpolation method, and the effects of alloying elements on precipitation behavior are manifested using weighted means of their diffusivities and concentration. The predictions were compared with the experimental measurements, and a good agreement was obtained.