text:  The Dvorak technique ( developed between 1969 and 1984 by Vernon Dvorak ) is a widely used system to estimate tropical cyclone intensity ( which includes tropical depression , tropical storm , and hurricane / typhoon / intense tropical cyclone intensities ) based solely on visible and infrared satellite images . Within the Dvorak satellite strength estimate for tropical cyclones , there are several visual patterns that a cyclone may take on which define the upper and lower bounds on its intensity . The primary patterns used are curved band pattern ( T1.0 @-@ T4.5 ) , shear pattern ( T1.5 @-@ T3.5 ) , central dense overcast ( CDO ) pattern ( T2.5 @-@ T5.0 ) , central cold cover ( CCC ) pattern , banding eye pattern ( T4.0 @-@ T4.5 ) , and eye pattern ( T4.5 - T8.0 ) . 
  