Because fluctuation in search trend data usually consists of multiple periodic components with characteristics of non- stationary and non-linearity, an adaptive-based method, such as empirical mode decomposition analysis, can be useful in isolating meaningful seasonal components. The EMD method provides a generic algorithm to decompose a complex time series into a set of intrinsic oscillations, called intrinsic mode functions, which oscillate at different time scales and are orthogonal to each other. We applied the EMD method to isolate a seasonal IMF in Internet search trends derived from 54 geographic locations worldwide. We aimed to test the following two hypotheses. The Internet searches for depression fluctuate seasonally, with increased search activity during the respective winter season in the northern or southern hemisphere. The seasonality of Internet searches for depression will depend in part on relative latitude; that is, those searches that originate from high latitude areas will be more seasonal. To investigate the search trend of depression on a global scale, we gathered local search trend data of health-related queries for depression originating from 54 geographic locations in the northern and southern hemispheres. Equivalent words representing depression were used in searches of non-English speaking countries. Because temperature change is Halothane mainly driven by exposure to sunlight and evidence has been found supporting the sunlight mediated change in the prevalence of depression, a solar influx model was used to approximate the daylight received at a given location and time in a year. The key finding emerging from this study is that health-related Internet search queries for depression are significantly correlated with temperature; this finding was evidenced by the fact that increased search activity was found during respective winter season in the northern and southern hemisphere. We demonstrate that this correlation is latitude-dependent, based on analysis of search trends over 54 geological locations worldwide. This phenomenon also exists universally across countries, regardless of language. Using Internet search query data as a signature of search Folinic acid calcium salt pentahydrate interests in depression, our findings support the common notion that people in higher latitudes are more vulnerable to low mood during the winter season than those in tropical areas. There are several implications of our findings. First, the Internet has become an important source of medical information in recent years and is increasingly influencing not only the practice of clinical medicine but also the population in general. Our findings of seasonal patterns are not exclusive to depression. Investigation of seasonal patterns in Internet search trends may aid future research in many disciplines, including epidemiology, sociology, or health care economy. For example, a specialized search query database has been used to predict influenza epidemics. With the appropriate regulation and protection of privacy of Internet search records, an effective, reliable prediction system for many important medical illnesses or psychiatric emergencies can be established. Second, prior studies regarding prevalence of seasonal mood disorders in different latitude have yielded inconsistent results. Using Internet data as a proxy of human affect, our analyses complement traditional approaches to epidemiological research on seasonal depression. The seasonal IMF significantly accounted for variability in raw search trend data ; its connection with seasonal depressive disorder may warrant future research.