From NOT A LOT OF PEOPLE KNOW THAT
By Paul Homewood
It’s worth taking a closer look at daily rainfall in Oxford, as it has such a long database, back to 1827. It tells us a lot about the weather in recent years, things that the Met Office want to hide from us.
Although we keep being told by the Met Office that our weather has been so wet in recent years because a “a warmer atmosphere can hold more moisture”, the principal factor is, and always has been, the number of days when it rains. In other words a meteorological phenomenon, not a climatic one.
The general definition of a rainday is when rainfall exceeds 1mm. The chart below plots these at Oxford. Data is from KNMI:
https://climexp.knmi.nl/data/pgdcnUK000056225.dat
Last year was 5th wettest and also featured high in the number of raindays. The years 2000, 2012 and 2014 also feature highly, as well as earlier ones such as 1872, 1916, 1927, 1951, 1958 and 1960.
Some periods have plenty of raindays, others much less. But there is no apparent trend in either direction.
But we can also analyse the average rainfall intensity, that is rainfall per rainday:
Last year had one of the highest intensities, in large part because spring and early summer was so dry. These are the times of year when daily rainfall is low, with mainly showery weather, so the overall average is bound to be exaggerated. But 2023 was by no means unusual, as there have been other years with similar rainfall intensity, such as 1915, 1949 and 1960.
More notable though is the occurrence of those years in the 1830s, when rainfall was clearly much more intense. Hardly evidence for the Met Office’s theory!
All of this is, of course, weather. I defy anybody to find a pattern or trend towards rainfall becoming more intense in Oxford in the above chart.
Again the overall trend suggests that rainfall intensity has been declining over the period of record.
Maybe the Met Office would like to explain.
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What’s with warm atmosphere holding more moisture? It’s cold air that can hold more moisture, why things dry out in your refrigerator. Sure relative humidity rises with temperature for the same water content.
Having been very aware for decades because I much dislike it when things remain wet or damp, everything most definitely dries faster when the temperature is higher. The opposite that you express makes no sense at all. Of course things dry out in the refrigerator. That is because the low temperature removes moisture from the air. That moisture ends up in the refrigerator’s drain pan, outside the refrigerator.
Evaporation rate is not the same as moisture capacity.
Ever wondered why it is so humid in the Tropics?
And you’re confusing relative humidity with absolute humidity.
Relative means with respect to what WV can be held at that temperature
Absolute describes the actual amount of water vapour in the air in g/m3. This also depends on the temperature of the air.
Relative humidity drops with rising temperature for the same water content.
My bad. I’m training to become a climate scientist.
No training (or self awareness) required for that gig.
Laugh, laugh
Sir, the reason why warm air can hold more water than cool air is not taught in high school or even in freshman physics of chemistry classes. I didn’t get this taught to me until I was a junior in college. We have found by both theory and experiment that the amount of water vapor that air can hold is related to a derived quantity known as the partial pressure. The partial pressure of water in air is equal to the mole fraction of water vapor in the air multiplied by the pressure of the air in absolute units. The partial pressure of water vapor can increase to the point where it equals the vapor pressure of pure water. It cannot go above that. Any attempt to humidify the air further results in droplets of liquid water forming, just like a cloud or fog bank.
The absolute humidity is the mass or weight of water in the air at a given temperature divided by the weight of the air+water mixture. The relative humidity is the mass of water in the air at that temperature divided by the maximum possible water in the air. This value is useful for heat transfer calculations by evaporative cooling (cooling towers) and for comfort of people.
For example, the vapor pressure of water at 30°C is 4.25 kPa or 0.616 psia. If we are at sea level, the atmospheric pressure is 101.325 kPa or 14.696 psia. Therefore, the maximum amount of water that can be held as vapor in air at this temperature and pressure is 4.25/101.325 = .0419 or 4.19%. if we are at a comfortable relative humidity of 45%, then the actual amount of water vapor in the air is 0.45*.0419 = .0189 mole fraction. That is .012 mass fraction or 1.2 wt%.
The vapor pressure of a liquid like water increases (exponentially) with temperature. At 100°C, the vapor pressure of water is equal to atmospheric pressure and water boils when heat is provided. Clouds form because humid air rises and cools until the partial pressure of the water vapor equals the amount that the air can hold as vapor. The excess begins to condense and form a cloud or fog.
The cold air blowing into the freezer is dry air. It’s called sublimation when your ice cubes evaporate when the temperature is below freezing.
Some unfair people accuse WUWT correspondents of cherry picking data to support their ideas. That is obviously unfair, as Oxford is internationally recognized as being a perfect representation of all other weather stations. Therefore, it is totally fair to use one small area to generalize about the climate.
He clearly states the reason he’s used Oxford – it has a database going back nearly 200 years.
He has but he is not seeing the data where the effect is taking place.
Where would that be…. in your mind ??
Mr Oxymoron.
Where I posted links to.
Now spray some bold/capped handwaving to deny it.
Poor little Anthony… Your life is really “sad” isn’t it.
The word “climate” has been redefined by the WMO to only be only 30 years, so they don’t look back at historical data.
No.
It is absolutely fair – as (as usual) Homewood has missed the point by not properly researching the MetO’s reasoning.
Increasing rainfall is highlighted by frontal rain events – (those containing extreme TPW) which persist over western/northern higher ground (orographically precipitated) and which will not affect Oxford.
See the return periodicity map I have posted elsewhere.
“ return periodicity“
So, it is all totally natural.
Explain why you are incapable…
…
… of posting anything to show human causation.
Obviously the MET Office will point to the early 1820s and show that there is now much more recorded rainfall than then.
See also the recent rise in named storms.
Here in the US there were some blizzards and snowfalls that earned a name in the past.
Then The Weather Channel started naming every winter stormfront and winters seemed to get much more severe (or should that be “more extreme”?).
The weather has been the usual crap
No change there
“Maybe the Met Office would like to explain.”
Why would they start now?
Why Oxford???? The UK as a whole tells a different story
Also if you look at flood warning issued in uk there is a probable rise (insufficient data for a definite on this)
During the later 20th Century and the 24 years of this century there has been a massive build out of housing estates on flood plains in the UK and the Environment Agency has a poor record of clearing waterways and maintaining flood defences. (Not entirely their fault – insufficient allocated funds also responsible)
So it is no surprise that there has been an increase in flood warnings but this tells you nothing about the rainfall pattern.
Why would Oxford be special case? I’d rather trust the consistent measuring at on place than a composite from many places widely apart with different lengths of recording.
The thing about this chart is it shows rainfall rising through the whole period. Maybe there is a slight pickup in recent years.
But according to the theory, Global Warming can only have been a factor for the last 50 or so years. So it may be that warming, due to natural factors for the first 100 years of the chart, causes increased rainfall. But the chart doesn’t support blaming it on human activity.
From this source…
UK monthly rainfall met office – Google Sheets
We get this graph of the period of rising CO2.
So again.. have you got any evidence of human causation??
“Again the overall trend suggests that rainfall intensity has been declining over the period of record.
Maybe the Met Office would like to explain.”
Mr Homewood:
They have done and it isn’t to be found within the Oxford rain data.
https://www.metoffice.gov.uk/research/climate/understanding-climate/uk-and-global-extreme-events-heavy-rainfall-and-floods
“Rainfall across the globe is determined by two things:
How warm the air is
Hotter air can hold more moisture. If the air has an unlimited water supply, such as an ocean, then warmer air draws up extra moisture. This results in clouds containing a greater number of larger rain droplets, and can be why showers in summer are often heavier than in winter. As the climate continues to warm, the effect will increase, and heavy rainfall events are expected to become more common.
The movement of weather patterns across the world
For example, the position of the jet stream near the UK influences a lot of our weather. However, any shifts in these weather patterns will lead to some regions becoming drier and others becoming wetter.”
https://rmets.onlinelibrary.wiley.com/doi/10.1002/joc.8167
“Annual count of the number of UK station-days which have recorded daily rainfall totals greater than or equal to 50 mm from 1961 to 2022, adjusted for station network size and excluding stations above 500 m above sea level. The table provides average annual values (station-days).”
There has been an increase of extreme rain fall events.
These over western/northern higher ground, where orographic influences are at play – that is most events come from frontal rainfall events (not convective event) – what here meteorologists call warm conveyors ( and the the US atmospheric rivers).
Hence cherry-picking a look at Oxford rainfall will elucidate nothing.
“The change in rainfall depends on location – for example, Scotland has experienced the greatest increase in rainfall, while most southern and eastern areas of England have experienced the least change. From the start of the observational record in 1862, six of the ten wettest years across the UK have occurred since 1998.”
Something happened around 1990 to also cause more sunshine hours.
Here are the rainfall patterns England for each month
The real peaks are circled in red. and they are not recent.
Well done for highlighting isolated weather events and not an increase in trends of extreme rainfall events – which is of course (?) obtained by looking at averages.
Outliers are always to be expected in any weather parameter and prove nothing.
If we constantly lived in “averaged” weather conditions, we’d have nothing to chat about, because no weather events would be noticed.
We all live in real world conditions, not numeric constructs conditions.
Averaged trends are what Homewood is “trying” to find lacking in order to criticise to MetO.
Hows about complaining to him … or alternatively just use your common-sense and realise that is all that can be referred to as evidence.
Dear God!
The “real world” can only be revealed by “numeric constructs” – else all we have are subjective feelings.
I do realize that counts for more for denizens here however
The real world is revealed the moment you extract your head from your anus.
Try it.
“Outliers are always to be expected in any weather parameter and prove nothing.”
That’s never stopped the IPCC from catastrophising the slightest deviation from average.
Yep, all the extreme rainfall months were well in the past.
Thanks for pointing that out !
Strange.. about a year ago, my water provider sent me a letter telling me I simply had to have a water meter fitted because the UK is getting dryer, so sayeth the Met office. But it was only about a year before that they were saying, and I quote, “the UK is now 6% wetter”. So I went to the Met office website, and sure enough they were then claiming that the UK is getting dryer. Back to today and now they are backing both horses:
“For example, the position of the jet stream near the UK influences a lot of our weather. However, any shifts in these weather patterns will lead to some regions becoming drier and others becoming wetter.”
I’m starting to think they are less than trustworthy.
Water usage is not entirely correlated with UK rainfall.
For a start it has to fall in the right places, and the reservoirs may/may not have enough reserve for the summer
No not drier…
https://www.metoffice.gov.uk/research/climate/understanding-climate/uk-and-global-extreme-events-drought#:~:text=As%20global%20temperatures%20rise%2C%20there,determine%20future%20UK%20drought%20risk.
“The latest State of the UK Climate report indicates the UK has become wetter over the last few decades, although with significant annual variation. 2011-2020 was 9% wetter than 1961-1990.”
“Winters across the UK are projected to get wetter, while summers are expected to become drier. However, it is the distribution of this rainfall that will determine future UK drought risk.”
I’m not going to post my address here, but I live somewhere on this map. As you can see, I am surrounded not only by reservoirs (red circles), but lakes, ponds, rivers, canals and even a couple of marshes and trust me, with the amount of rain we’ve had in this area over the last few months, they’re all full. There is no water shortage now, nor has there ever been in this neck of the woods that I can remember. What there is, are lame excuses for charging more and more for less and less. The Met office backs up the alarmist narrative no matter which way it drifts.
‘A warmer atmosphere can hold more moisture’ is the usual weasel-word mantra.
It ‘can’, but ‘does’ it? Why ‘can’? Because of Clausius Clapeyron, an equilibrium equation for a closed system in thermodynamic equilibrium. The atmosphere is neither. It’s an open system in a permanent state of non-equilibrium.
Looking at it from another point of view, the mantra implicitly assumes that the relative humidity is something of a conserved characteristic (or close to it) in the climate system. There is no known physical principle why that should be the case. Nor is there observational evidence for it. In fact, there is not one climatologist who can tell us what the relative humidity ought to be. For the atmosphere as a whole it is (apparently) about 60-70%, but nobody on the planet knows why it is not 80% or 40% and as long as we don’t know any statement about atmospheric water content is speculation.
Start making observations.
Ed, there are observations. Go to climate4you and then click on “climate + clouds. There you will find atmospheric relative and specific humidity data and total column water vapor as well going back to the early 80’s. As you will see, all have been declining for the past 40 years.
There are inconvenient truths in many of our long term climate records since all lies are, by definition, convenient. Of course if meteorology had remained a true profession there wouldn’t be any place for lies or misrepresentations of any kind.
If the UK Met Office has nothing to fear about UK long term weather records in respect of change then why would they spend so much time modifying data or cherry picking it and/or adding red to the colour spectrum in charts just to emphasize their inappropriate belief system?
In the next year or so, they will probably be claiming MORE DROUGHTS in the UK ! 🙂
England drought declared in parts after months of scant rainfall | CNN
Summer 2022 drought provides warning for future years | UK Centre for Ecology & Hydrology (ceh.ac.uk)
In the next year or so, they will probably be claiming MORE DROUGHTS in the UK ! 🙂
England drought declared in parts after months of scant rainfall | CNN
Summer 2022 drought provides warning for future years | UK Centre for Ecology & Hydrology (ceh.ac.uk)
Oh look , its already happened.. 🙂
Summer 2022 drought provides warning for future years | UK Centre for Ecology & Hydrology (ceh.ac.uk)
iirc, they even invented a new term just for the “VERY SCARY” factor.. “flash drought”
Surely it’s obvious. In climate land the more rain you have the more droughts you have and vice versa 🙂
Add “Atmospheric Rivers” and “Bomb Cyclones” to their new sensationalized terminology.
sorry, I don’t know why I’m getting posts doubling up ! ??
Just another thing that’s caused by global warming.
You can say that again.
The USEPA has published a chart showing rainfall changes globally since 1901. The chart shows that rainfall has been increasing at a rate of 0.04 millimeters per decade over the past 120+ years. That’s 0.004mm/year or 0.0002 inches per year. The earth’s average rainfall over land is about 46 inches per year including much more over equatorial jungles and practically nothing over deserts.
I think the question is not whether rainfall is increasing or decreasing but why should it be so steady? Rainfall over a fairly small area such as the UK is a weather question requiring focus on just what changes have or are occurring over or near that area. Any changes in recent times are clearly not a global climate change issue.
“Rainfall over a fairly small area such as the UK is a weather question requiring focus on just what changes have or are occurring over or near that area. Any changes in recent times are clearly not a global climate change issue.”
I don’t think the UK is a good example of anything “global”. The UK has a rather unique situation: It is warmed by the Gulf Stream effect and is surrounded by oceans, so its weather is going to differ from other areas of the globe that are not warmed by the Gulf Stream effect, or are surrounded by oceans.
The energy the Earth receives from the Sun has increased over the last 100 years compared to the previous 300 years, warming the oceans.
https://lasp.colorado.edu/lisird/data/historical_tsi
I defy anybody to find a pattern or trend towards rainfall becoming more intense in Oxford in the above chart.
Well Blind Freddy can see you’ve left out the tree rings for starters. We’re busy people at the Met Office and don’t have time for this amateurish display.
“I defy anybody to find a pattern or trend towards rainfall becoming more intense in Oxford in the above chart.”
Well that’s because there isn’t expected to be one.
As I have explained elsewhere, Homewood is (as usual) doing his reflexive UKMO rubbishing without having position of the facts of what the MO is saying.
Data shows all the most extreme monthly rainfalls were well in the past. (as shown earlier)
Denial of data… it is an AGW-cult thing… always. !
That’s fine rubbishing soothsayers and doomsters because Gavin and Co with all the King’s horses and all the King’s men haven’t got a clue what’s going on either with their pathetic and infinitesimally short period thermometers-
The world has been its hottest on record for 10 months straight. Scientists can’t fully explain why – ABC News
If the thermometers don’t fit the computer models then just graft on some tree rings or tea leaf readings and put out another press release with ‘it’s worse than we thought’ and get back on the bong or whatever medication gets you through the night. Just stop upsetting the kids with the dooming before we all die and let them play and have fun before we have to administer the Kool Aid. Stiff upper lip and all that for grownups.
I would like to see as the first graph the rainfall totals per year at Oxford.