Dew Point can either be measured via an instrument called a hygrometer, or it can be computed based on relative humidity. Higher dew points represent higher levels of moisture content in the air at a given temperature whereas lower dew points represent lower levels. When the dew point temperature equals the temperature of the air, the air is saturated. The dew point temperature can never exceed the temperature of the air.
Measured or computed dew point values can be specified directly within HEC-HMS using the Specified Dew Point Thermograph Method.
Required Parameters
At least one Temperature Gage, created as a Time-Series Data object, with measured or computed dew point temperatures must be input to use this method. Values may be specified in units of Fahrenheit or Celsius. The user will assign a temperature gage to each subbasin within the Meteorologic Model editor.