By EBUN SESSOU
Abayomi Oyegoke, is the Chief Meteorologist of the Central Forecast Office of the Nigerian Meteorological Agency, NIMET, Lagos. In this interview, he bares his mind on some issues surrounding rainfall and how it can be diverted. Excerpt
What is your position on the prediction that there will be 236 days of heavy rainfall in Lagos State?
The initial prediction by the Lagos State Government that there would be 236 days of rainfall for the year 2012 was a misinterpretation. It was a wrong interpretation of what we gave out in our seasonal rainfall prediction.
What we have in our seasonal rainfall prediction was misinterpreted by the commissioner. What we are saying is that the rainfall will commence between February 24 and March 30 and as God would have it, the prediction came up, we had rain on February 24, 2012 which made it a perfect prediction. And what we are saying is that there will be possibility of the rain ceasing between November 4 and 11, 2012.
By that calculation, we arrived at the figure quoted by the commissioner but that doesn’t mean it will rain within the period of 236 days. We are only saying that this is the duration when Lagosians should expect rain not that it will be raining everyday.
Are you predicting heavy rainfall?
Going through our seasonal rainfall prediction, we made it clear that Nigerians should expect normal rainfall this year. It has been said categorically that the rain will be normal and we are still looking at the normalcy of the rain as it should be.
Would there be ?
We cannot rule out storm over the country. A good example was the storm that blew off roofs, destroyed properties recently. The fact is that when rain is about to commence, it comes along with strong wind which meets with thunder storm and that is felt on heavy downfall. And that is when we say, there is storm. So, it is not possible to rule out stormy rainfall completely, but we will always announce it in advance, so that people will be prepared for it.
What is your take on rainmakers causing rainfall?
We all grew up in the villages but field of science doesn’t believe in that. Although there are some thermodynamics that should be involved before we can say, there will be rain. And as much as those thermodynamics are concerned, nothing can stop rain when it is time. And if the conditions are not there, there are possibility that it will not rain. But, if they have another means of meeting the conditions that cause rainfall, whether by diabolical means, I will not contest that but the field of Science does not believe that people can hold or cause rainfall.
What about the idea that rain can be diverted?
It is possible and that is what is called, rain seeding. It is done in developed countries and just as I have just mentioned. There are certain conditions that are required. In developed countries, certain chemicals will be released into the atmosphere when they desire that it should rain in certain areas. When those conditions including sodium, chlorine are released in the atmosphere, when it goes up, it fastens the cooling of the air, and by the time it gets to super cool, the next step is to come down. And when you don’t want it to fall in an area, they use aircraft to blow it to the area they wanted. So, people in developed countries use aircraft to release chemicals into the atmosphere and so, rain is blown into another region they want. But, Nigeria is still developing, we are not in the position of seeding our rain.
We heard that some construction companies are in the habit of holding rain, what is your take?
My research hasn’t revealed that aspect to me. But,we are still developing and what we believe is that there are conditions to be met before the cloud we saw up can come down in form of precipitation (any form of rain droplet) it may be rainfall, drizzling, ice pellets, and until those conditions are met, I doubt the possibility. It is a rumour, but scientifically, we can seed rain.
What is the percentage probability of having rainfall?
What we call forecast is a prediction and it is probability and there are percentage of probability. If the probability is above 60 and 70 percent, then the prediction will come to pass. But if it is below average say, below 50, it might not rain. And because it is a probability, we might have seen a system developed that is ripe enough to come down in form of rain, but some conditions might come and change the position. This cloud upstairs, contains some classes of wind that are lifted up and it comes cold, super cold, saturated, over saturated and before nuclear agent combated it and melted it down. And as this is happening, another dried wind (wind with less water vapour) came from nowhere and blowing into that kind of system that is already saturated, it might siphon the water in the system, buoyant with moisture and once it siphoned it, it will eventually dry off. When it happens, there are always update from the department of meteorologic that the system we saw that is coming has dried off. When we talk of wind, it is air in motion, it is not static, and as it is moving in an environment, it meets different environments and when it gets to an environment that is buoyant, it gets more energy to grow and the possibility of coming down in form of rainfall is a greater percentage but when it comes into an environment that is dry, the environment will choke up the moisture inside it and dries it off.
Even with dark cloud, is it impossible for rain not to fall?
The reason is what I just explained. Once, the environment is not satisfied for the buoyancy of the air or the Eco-system that we are witnessing, that it is about to fall, it dries off. And that is why everybody uses the language that “it has been blown away”. Maybe that is what people refer to as “holding the rain”. But the field of science does not believe that people can hold rain because we know the conditions for rain to fall and not to fall.
What is the effect of all of these?
As a developing country, we rely mostly on farm produce and our farm produce relies mainly on the amount of rain that fall, so if it refuses to rain, then, it will affect the economy of this country. If there is no rain, there will be drought over the country which might lead to famine. That means, there will be no enough food for the common man on the street to eat. But for the fact that the rain has just commenced, it is expected that it will be like this but it doesn’t mean it will rain. Rain will eventually come, just by our prediction and the country should look out for normal rain this year.