Higher temperatures are usually reported during meteorological drought and there are two prevailing interpretations for this observation. The first is that the increase in temperature (T) causes an increase in evaporation (E) that dries the environment. The second states that the decline in precipitation (P) during drought reduces the available water thereby decreasing E, and in turn the consequent reduction in evaporative cooling causes higher T. To test which of these interpretations is correct, we use climatic data (T, P) and a recently released database (CERES) that includes incoming and outgoing shortwave and longwave surface radiative fluxes to study meteorological drought at four sites (parts of Australia, US, and Brazil), using the Budyko approximation to calculate E. The results support the second interpretation at arid sites. The analysis also showed that increases in T due to drought have a different radiative signature from increases in T due to elevated CO 2 .

Arid and semi-arid environments present challenges for ecosystems and the human activities within them. Climate classifications are one method of understanding the climate of these regions, giving regionalscale insight into parameters such as temperature and precipitation. This essay qualitatively compares the application of four different climate classification schemes (Köppen-Trewartha, Guetter-Kutzbach, De Martonne and Erinç) to a transect across Western Australia. The classification schemes show a distinct climatic gradient from the wet coast to the dry continental interior, with the most pronounced gradient located near the coast. Strong agreement is found between weather stations and classifications for wet and dry years, indicating that the weather systems on the coast also govern weather inland. Historically wet and dry periods, as well as long-term drying trends were also identified for the coastal regions, which could affect the livelihoods of many people. A long-term drying trend is also evident at Kalgoorlie-Boulder, the most arid, inland town. These results show that climate classifications can identify major trends and shifts in climate on a decadal or yearly basis, and it is hoped that they will become more widely used for this form of analysis.