What is 1/2" of irrigation?

Irrigation Requirement (ETc - Effective Rainfall) Last 7 Day -0.22" Last 24 Hour 0.00" Rain Rain (Last Hour) 0.00" Rain (Last 24 Hour) 0.00" Rain (Last 7 Days) 0.28" Air Temperature Last Hour Average 19.8° Daily Average 23.0° Daily Maximum Temperature 29.9° Daily Minimum Temperature 17.3°		Relative Humidity Relative Humidity Avg 79.1% Wind Wind Speed Avg 0.4 m/s Reference Evapotranspiration (ETo) Todays ETo 0.04" Last 24 Hour ETo 0.03" Last 7 Day ETo 0.19"

Last 7 Days
ETc vs Irrigation Requirement (Net ETc)	Humidity & Temperature	Temperature and ETc
Last 30 Days
ETc vs Irrigation Requirement (Net ETc)	Humidity & Temperature	Temperature and ETc
Year To Date
ETc vs Irrigation Requirement (Net ETc)	Humidity & Temperature	Temperature and ETc

January	March	May	July	September	November
February	April	June	August	October	December
Last Year Summary By Month (2007)			This Year Summary By Month

ALL STATION DATA, HOURLY