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Charts - Rain charts: Difference between revisions
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The Rain charts submodule consists of | The Rain charts submodule consists of five charts: | ||
#Daily Rain - Plotting the rainfall for every day in the dayfile; | #Daily Rain - Plotting the rainfall for every day in the dayfile; | ||
#Monthly Rain - Plotting the monthly rainfall for every year in the dayfile | #Monthly Rain - Plotting the monthly rainfall for every year in the dayfile | ||
#Yearly Rain statistics - Plotting the average, range and standard deviation for for the rainfall in every year | #Yearly Rain statistics - Plotting the average, range and standard deviation for for the rainfall in every year | ||
#Yearly Rain statistics per month = plotting the average, range and standard deviation for for the rainfall in each month in every year | #Yearly Rain statistics per month = plotting the average, range and standard deviation for for the rainfall in each month in every year | ||
#Rain versus EvapoTranspiration (EVT) | |||
Below you will find an example image of each chart and an explanation of the origin of the numbers | Below you will find an example image of each chart and an explanation of the origin of the numbers | ||
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[[File:Year Month Rain Statistics.jpg|thumb|right|Yearly Rain statistics per Month]] | [[File:Year Month Rain Statistics.jpg|thumb|right|Yearly Rain statistics per Month]] | ||
This chart is similar to the previous one, only now the the user can select a specific month through a row of buttons on top of the chart. | This chart is similar to the previous one, only now the the user can select a specific month through a row of buttons on top of the chart. | ||
== Rain versus EvapoTranspiration (EVT) == | |||
[[File:RainVsEVT.png|thumb|alt=Rain versus EvapoTranspiration (EVT)|Rain versus EvapoTranspiration (EVT)]] | |||
The cumulative rain is plotted versus the cumulative evapotranspiration. The latter coming either from the device (Davis) or calculated by CMX. The plot is implemented as a coloured area plot showing a surplus of rain in green and a rain deficit as red. Best is to show some years from the start of the rain season (use the date selector). | |||
This chart is an effort to graphically display droughts. It must be understood that EVT is a very complex meteorological aggregate in that it is highly dependent on the interaction between soil, vegetation and meteorology. CMX uses only one equation for all situations on earth. That equation seems to be fitted to the moderate climate. As such it bypasses plant strategies to battle drought and low humidity situations such as the stomata closure and deep rooting. The chart as such must be used with some caution. | |||
It is advised to always use the CMX calculation as that would result in comparable charts. CMX uses the [https://www.fao.org/3/x0490e/x0490e08.htm#calculation%20procedure FAO Penman-Monteith equation] with [https://github.com/weewx/weewx/blob/master/bin/weewx/wxformulas.py#L776 reference to the implementation of Weewx]. | |||
The user is advised not to take the EvapoTranspiration figures as absolute but, for a good understanding of the complexity of EvapoTranspiration, to study the relevant chapter [https://www.fao.org/3/x0490e/x0490e00.htm#Contents ''FAO Crop evapotranspiration - Guidelines for computing crop water requirements - FAO Irrigation and drainage paper 56'']. | |||
[[Category:CumulusUtils]] | [[Category:CumulusUtils]] | ||