# Hourly Air Temperature Air temperature data are usually provided in the form of daily maximum and minimum temperature. A reasonable approximation for converting these to hourly temperatures is to assume a sinusoidal interpolation function between the minimum and maximum daily temperatures. The maximum daily temperature is assumed to occur at 1500 hours and the minimum daily temperature at 300 hours (Campbell, 1985). The temperature for the hour is then calculated with the equation: $$T\_{hr} = \overline T\_{av} + \frac{T\_{mx}-T\_{mn}}2 *cos(0.2618*(hr-15))$$ 1:1.3.1 where $$T\_{hr}$$ is the air temperature during hour $$hr$$of the day (C), $$\overline T\_{av}$$is the average temperature on the day (C), $$T\_{mx}$$ is the daily maximum temperature (C), and $$T\_{mn}$$ is the daily minimum temperature (C). Table 1:1-6: SWAT+ input variables that pertain to hourly air temperature. | Variable Name | Definition | File Name | | ------------- | ------------------------------------------ | --------- | | MAX TEMP | $$T\_{mx}$$: Daily maximum temperature (C) | .tmp | | MIN TEMP | $$T\_{mn}$$: Daily minimum temperature (C) | .tmp | --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://swatplus.gitbook.io/io-docs/~/changes/GiVD5ID0WVyRIAumaMy2/theoretical-documentation/untitled/temperature/hourly-air-temperature.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.