zenithalHourlyRate

Given a predicate that represents a relationship or action between entities, generate a one-sentence description explaining its meaning.  
# Instructions
Focus on describing the relationship, not the entities themselves. 
# Response Format
Begin the description with \' Indicates...\'

Predicate: zenithalHourlyRate

Indicates the rate at which a quantity (typically radiant or particle flux) is received per hour when the source is positioned at the zenith directly overhead.