Basic engg. data

[mohtogh]

For starting the design of a plant we need some parameters such as temperature,rain ....
for each parameter we have a "maximum absolute " and also "maximum average" of parameter .(And also for minimum).
I have two question about this:
1. What type of above mentioned parameters should be used?max. abs. or max. avg. ?
2. What is the method for obtaining such data from e.g. daily ambient temperature?
Thanks

 

[eyadamk]

1-In design consider the worst case to avoid the worst so have the abs. values.