Model to create rain Eddie Miller Port Elizabeth

THERE have been many complaints about weather forecasting and some people advocate using Norwegian weather forecasting sites and so on.

Because air heats up from infrared radiation from the ground (terrestrial radiation) and air is absorbing radiation more with more carbon dioxide, I am not surprised that weather models have to adjust.

But I am one for rain enhancement and would like to do my own calculations on what happens to air parcels from heated sea and so on. Fortunately, the ratio of mass of water vapour to the mass of dry air in a parcel remains constant whether you heat the parcel or compress it.

This ratio is called the humidity ratio and once you have found it (when the parcel starts to rise, for instance) it will remain unaltered if the parcel air does not mix with the surrounding air.

Air masses of different humidity and temperature do not mix easily.

This is because air is not a good conductor of heat, the hotter rises above the colder, and if the hotter one is cooled where it contacts the cooler mass, condensation often occurs and the heat of condensation keeps the hotter parcel warm.

Now if we know the initial humidity ratio of the parcel (which largely stays constant) we only need to know the temperature and pressure of the air parcel to calculate the relative humidity (RH) at any time.

So we can calculate when RH will be 100% and rain is likely.

This could allow us to estimate how much we must heat the sea surface with floating black plastic sheets (knowing wind speed and direction) for the parcel to create rain in our chosen area.

Heat gain by terrestrial radiation and pressure (from altitude) could be estimated for the predicted path of the parcel.