WEATHER GURU | Does fog in the morning mean we are in for a hot day?


Many believe that when there is fog or mist in the morning at this time of the year, it is a sure sign of a hot day ahead.

Being in the catering industry, my wife and her staff know it’s going to be a visit to the proverbial “Hell’s Kitchen” that day.

I then ask myself if her “weather forecasting” skills are as good as her cooking skills.

Is this theory true or an old wives’ tale?

February to April are the months with the most fog in Nelson Mandela Bay, with the peak in March.

January to March have the greatest number of days with maximum temperatures above 25C.

Just from this, my wife’s  theory must hold ground. She and her staff’s personal experiences in a kitchen with four gas burners and two double ovens running the whole day must hold some ground as to her forecasting abilities.

As this is the time of the year with a predominantly easterly flow (sea land breeze), there is always sufficient moisture for the formation of fog, especially after hot days.

We often see the low clouds and fog sitting over the sea, waiting for enough cooling to make landfall.

Then we often have what we call a temperature inversion, which is where we have a rise in temperature with a rise in altitude (height).

This is the opposite of the norm where one gets colder the higher one goes in the atmosphere.

The point at which the state of the temperature returns to norm is known as the temperature inversion.

The inversion can trap moisture or impurities below it and the surface temperatures need to reach the temperature of the inversion to dissipate the fog.

Thus, it is a rise in temperature that will dissipate the fog. This also gives more credence to Mrs Guru’s theory.

The heating of the earth’s surface to dissipate the fog generally comes from north-westerly winds (hot land sea breeze) and thus raises the temperature. Another point to Mrs Guru.

Persistent easterly flow can keep the temperature down with added moisture.

This happened in 1982 while I was doing military service in the Air Force. On a weekend pass the fog moved in and did not let up for three days.

This meant that there were no flights to return to Valhalla, Pretoria, thus extending my time with my girlfriend (future wife).

Maybe this was divine intervention as I never experienced a situation like this in the Bay again.

I did in Walvis Bay where, according to numerous authors, the thickest and worst fog in the world occurs.

I can attest to that as flights were only scheduled for the afternoons in the time I spent there because it was too dangerous for aircraft to land in the morning due to the heavy fog.

This week in history:

1961: As a prelude to 1968, floods were recorded in the then-Port Elizabeth.

Weather safety tips:

With the hot and humid weather and load-shedding, air conditioners take strain at this time of the year. For the old and infirm have a backup.

Always dry up excess water as it can lead to accidents, be it slipping or, in extreme cases, electrocution.

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