Which resource is most appropriate for a middle school student seeking average winter temperatures worldwide?

The most appropriate resource for a middle school student seeking average winter temperatures worldwide is a general almanac. Almanacs are designed to provide a wide range of statistical data, including information on climate and weather patterns over time. They compile average temperatures, seasons, and other relevant data in an easily digestible format, making them ideal for students conducting research or looking for specific information.

While a general encyclopedia (the first option) offers broader summaries and thematic overviews, it may not provide the precise data related to temperatures that the student is looking for. A scientific journal typically contains peer-reviewed articles that present detailed research findings, which may be too complex or technical for a middle school student. Lastly, although a weather forecasting app provides current weather conditions and forecasts, it does not focus on average temperatures over a specific time frame such as winter, making it less suitable for the student's needs. Therefore, the general almanac stands out as the best resource for this particular inquiry.