How do I determine icing conditions
This may sound like a silly question, and it probably is, but how do I determine icing conditions?
Taking today as an example, according to the Metar data for East Midlands it is +5C with a due point of +4C.
I am therefore assuming that at 500ft, the relative humidity will be 100% and above this altitude there is sufficient moisture to cause icing should the temperature drop below zero. On this same basis, icing conditions will be present above 2,500ft assuming ISA conditions with a temperature drop of 2C per 1000ft.
Is that correct or do other circumstances need to be taken into account such as presence of cloud etc?
Can icing conditions occur below 100% relative humidity?
Do icing conditions always occur when temperature is below zero?
Thanks
Jon