How Much Water Vapour Is In A Cubic Metre Of Air at A Given Temperature And Relative Humidity?
I needed to know this as if I knew the temperature and relative humidity in my bedroom, when I went to bed and got up, I could work out how much water vapour had transferred to or from the air during my sleep.
One of my friends at school is an expert on these sort of calculations for industrial clients.
He came round on Friday night and we discussed it through, but I don’t think I got more than a basic grasp.
The reason is that he works from charts, whereas all my working life, I’ve started with proven formulae and worked everything out from first principles. But then I trained as a Control Engineer.
A problem I had with the psychometric charts he uses, is that they are all in a measurement system, that is totally foreign to me – Imperial. This is because most of the publishers are across the pond and they still use units, I last used in my early teens. When I went to work at ICI in the late sixties, the company had metricated in 1955 or so.
At least after our meeting and discussion, I now know what I’m searching for.
I finally found this web page, which gives a table of saturated vapour density for water in air. Although, it’s an American web site, at least it gives this in gm/cu. m.
The web page gives the SVP in gm/cu. m. at various temperatures
- 0°C – 4.85
- 10°C – 9.4
- 15°C – 12.83
- 20°C – 17.3
- 25°C – 23
- 30°C – 30.4
- 37°C – 44
- 40°C – 51.1
As an illustration, suppose you have a temperature of 25°C and a relative humidity of 50%. I measure it on my Maplin meter.
Maplin Hygro-Thermometer
At that temperature a cubic metre of water can hold 23 grams of water. But as the relative humidity is 50%, it is actually only holding 11.5 grams of water. As my bedroom is about five metres square and two and a half metres high, that means the room contains over 719 grams of water.
Now look at 30°C and the same relative humidity of 50%.
The same calculation gives 950 grams of water in the room.
So if with the central heating, the electric blanket and the fact that each person probably is equivalent to a one bar electric fire, your bedroom, about the same size as mine, goes from say 25°C to 30°C, the air will need another 230 grams of water to be in equilibrium, or in layman’s terms, happy with how it relates to everything.
So from where does the air get this water it needs?
You!
No wonder a lot of people go to bed with a night bucket, so they can replenish the fluid they’ve lost to the air.
Scatty Middle-Aged Mum ‘Reborn As Jihacker’s Wife’
This is the headline to a large piece in the Sunday’s Times, describing how a white female convert to Islam is tweeting offensively from land controlled by the Islamic State.
Surely, many of those who have gone to support the cruel and extremely violent regime in the Middle East would be how those that are best described as several bricks short of a full load.
Are we building enough secure mental hospitals?
A Surprisingly E-Mail From A Lady
I just had an e-mail from a well-brought up lady, which mentioned the word, Arseblog.
It’s not about what it could be, but the name of a blog, that provides text commentary for the well-known London team, that she supports.
Disappearing Balances
One of my old school friends came round last night for a drink and a chat. At one point, I used my letter balance to weigh something.
My All-Purpose Balance
They said, that at the University, where he works, they have given up on expensive weighing machines and now use cheap letter balances, as the students nick them, to weigh out their drugs.
Such is University life these days!
Another Talking Statue
I took this picture of the war memorial on platform one at Paddington station.
Another Talking Statue
A voice track has now been added.
Guns Kill People
When I read stories like this one from Arizona, I despair. Here’s the first paragraph.
A nine year-old girl in the US has killed her shooting instructor by accident while being shown how to use a high-powered automatic weapon.
I always feel edgy when guns are around. I think I have good reason and believe strongly that the world would be a better place,if guns had not been invented.
What Is Natural Oak?
I found this advert rather strange.
What Is Natural Oak?
I suppose unnatural oak would be veneered chipboard or MDF.
They’ve Given Hugh A Voice!
Islington is unusual in that the most prominent statue in the main commercial and shopping area of the town is not of royalty, a politician or a military figure, who is probably best forgotten.
Statue Of Sir Hugh Myddelton On Islington Green
Their main statue on Islington Green is of Sir Hugh Myddelton, who is described like this in Wikipedia.
Sir Hugh Myddelton (or Middleton), 1st Baronet (1560 – 10 December 1631) was a Welsh clothmaker, entrepreneur, mine-owner, goldsmith, banker and self-taught engineer
The statue stands where his main creation; the New River, ended its journey to bring fresh water into London. I suppose a modern equivalent would be to put a statue of Lord Coe in the Olympic Park.
They’ve now given Sir Hugh a voice, which you can listen to on your mobile phone.
Listen To Sir Hugh
This picture shows a close-up of the plaque, which details how you listen. This link takes you there.
The Real Winners In The Scottish Referendum
I’ve just looked up the betting odds for the Scottish Referendum on Odds Checker.
Typical prices as I write this are.
No! – 1/8
Yes! – 9.2
The bookies are usually right and with these odds, I think there can be only one winner.
But odds change, so check the current odds before making a decision.
If I had a vote in this referendum, I would not have been impressed by the performance of Darling and Salmond. But then whenever I see a man called Darling, I’m reminded of Blackadder.
Does The NHS Need Physician Associates?
There have been reports about using these in the NHS over the last few days. One article in the Independent is entitled, NHS patients to be seen by doctors on the cheap. It starts with.
Patients will increasingly be seen by “physician associates” rather than doctors under Government plans despite fears they are “doctors on the cheap”, according to a report.
I have seen a lot of doctors and hospitals over the last ten years, what with the death of my wife and son to cancer and my stroke. What is different now, to what I remember of the NHS in the 1960s and 1970s, is that nurses now play a larger role.
Does anybody bother?
Some might, but I’ve never heard anybody complain, that the nurse did a job, that a doctor might have not delegated forty years ago.
So when it comes to physician associates, I have an open mind.
Or I did until I read the letters page of The Times today, where four serious letters from eminent medical professionals were very much supportive of physician associates.
Now I’ve changed my open mind to one that is totally in favour!
The Anonymous Widower 