Formation of Radiation Fog - T = Td

  • Once the temperature reaches the dew point, radiation fog begins to develop

  • Common in the fall - especially when our weather is dominated by high pressure

  • often forms in valleys first since this is where the coldest air is - called valley fog

  • Q: Do radiation fogs develop upward or downward?? ANSWER

  • Q: When is radiation fog the thickest?? ANSWER

  • Data examples:

  • Photo example #1

  • Photo example #2