UK to bake in 33C amid extreme heat warning

[Greg2607]

https://www.thelocal.fr/20220811/in-pictures-french-drought-intensifies-loire-dries-up/

 

people really do need to wake up.... 

 

Beavers are part of the solution.... hopefully they quickly establish in the UK. 

[SpacedX]

6 hours ago, SkidsFox said:

I'm looking forward to next week's storms. Could see some amazing downpours (warmer air can hold more water).

Air does not 'hold' water. Saying that warm air "holds" more moisture is technically incorrect, but is a common misconception. Saying cold air 'can’t hold as much water vapour as warmer air' is at best a metaphor for observed reality, but It’s a metaphor that can lead people astray in the understanding of meteorology. 

 

Consider a glass of water. Water molecules in liquid are in motion in accordance with varying kinetic energies and consequently different speeds. Some will be slow, others will be faster. The average kinetic energy or if you like 'speed' of the molecules is defined as the temperature of the liquid. Put more energy into the liquid (by heating it for example) and the average speed of the molecules increases. Intermolecular forces in the liquid generally prevent most molecules from escaping, but the most energetic molecules are able to break free from the liquid if they get close to the surface between the liquid and the background medium (gas or vacuum). At this stage the molecules are no longer part of the liquid, but are now existing in the form of water vapour. Molecules in water vapour also have a wide range of speeds and if the slower molecules strike the surface of the liquid they can be caught and transition from the gaseous phase to the liquid phase. Just like in the liquid, the average speed of the molecules in the water vapour is governed by the temperature.

 

If we imagine a closed room containing some body of liquid water - say the glass, there will be a constant exchange of water molecules leaving the liquid as water vapour and molecules of water vapour having too low energy to escape the liquid and becoming part of it. Assuming an absence of ventilation or other outside influence, eventually an state of equilibrium is reached between these two directions and the amount of water in each phase remains constant. As with any gas, the water vapour in the room exerts a pressure. The term "partial pressure" refers to the pressure that a component of the gas has if it were the only thing present in a volume. Therefore, at a constant temperature, according to the ideal gas law, this pressure is proportional to the amount of water vapour present. So the partial pressure of the water vapour is a measurement for how much water there is as vapour (per unit of volume). So in the example of a sealed room hypothetically in a constant state, the exchange between liquid and vapour phase is balanced out, we say that the situation has reached an equilibrium and the the partial pressure of the water vapour in this situation is called the equilibrium vapour pressure. This depends on the temperature of the liquid and of the vapour. With higher temperatures, more molecules in the liquid will have the speed to break free from the liquid and enter the vapour phase and fewer molecules in the vapour will have an energy low enough to be absorbed into the liquid. And vice versa with lower temperatures. So at higher temperatures, the partial pressure of water vapour can be higher. That means that the space - in this case the room - can contain more water vapour. This same space is often also occupied by the air, but it is not the air itself or its properties that determine how much water vapour can be present in the space.

 

The other important consideration is relative humidity. This is defined as the ratio of the current vapour pressure to the equilibrium vapour pressure. Returning again to the example of a sealed room, the relative humidity will eventually reach 100%. If the relative humidity is less than 100%, then water in liquid form will evaporate at a higher rate than vapour will condense. If there is some form of ventilation, as is the case in most houses, this means that a volume of liquid water will completely evaporate given enough time. If the relative humidity is above 100%, we speak of supersaturation which is the process that allows clouds to form, expand and increase in mass or aircraft contrails to spread across the sky. The rate of condensation will exceed the rate of evaporation - or more accurately in this case, sublimation, and water will start to condensate through coalescing onto condensation and hygroscopic nuclei. The relative humidity depends on the temperature as well as the absolute amount of water present in vapour form, since the equilibrium vapour pressure depends on the temperature. 

 

Sorry if this seems pedantic - this isn't directed at you. Of grave concern are individuals to whom the public is dependent upon, especially during our current time of climate crisis, who unintentionally misrepresent basic concepts of meteorology. Such as “warm air ‘holds’ more water than cooler air.”  I probably didn't need to type all that - apologies. Simply that in terms of the phase changes I referred to, yes evaporation occurs more frequently at higher temperatures but this had absolutely nothing whatsoever to do with the air being able to ‘hold’ more water because of higher temperatures. Evaporation occurs more frequently when an air parcel is at higher temperatures because very simply the molecules have greater energy and are therefore moving more quickly.

 

The takeaway from this is the realisation that air has no holding capacity whatsoever. Therefore the claim that warm air “holds more water” than cooler air is completely fallacious. if you hear any source of weather information making this claim, then its purely as a means of easing understanding (incorrectly) and for the purposes of simplification. 

Edited 11 August 2022 by Line-X

[yorkie1999]

42 minutes ago, Line-X said:

Do you understand why? 

Yes, because the ground is so dry that the rain will will cause flooding. Everyone in the world knows this and it's been like this for a million years. Imagine, though, if someone had the bright idea of digging a few holes in the ground in places around the country that acted as resevoirs to collect the floodwater, in addition to the resevoirs we already have. I mean, it's not as though we don't know which areas are prone to flooding after sudden rainstorms.

[String fellow]

Trying to look for positives, the day-length is reducing by about 3.5 minutes at present, and today dropped below 15 hours in total. In late June, it was almost 17 hours long. And at its highest point in the sky, the sun is now 8 degrees lower down than in late June. So winter is approaching, when instead of moaning about the heat, we'll be able to moan about the cold - especially if there are power cuts. 

[Nalis]

30 minutes ago, Greg2607 said:

https://www.thelocal.fr/20220811/in-pictures-french-drought-intensifies-loire-dries-up/

 

people really do need to wake up.... 

 

Beavers are part of the solution.... hopefully they quickly establish in the UK. 

Guaranteed likes from JattDogg and MikeOxlong incoming

[SpacedX]

1 minute ago, yorkie1999 said:

Yes, because the ground is so dry that the rain will will cause flooding. Everyone in the world knows this and it's been like this for a million years. Imagine, though, if someone had the bright idea of digging a few holes in the ground in places around the country that acted as resevoirs to collect the floodwater, in addition to the resevoirs we already have. I mean, it's not as though we don't know which areas are prone to flooding after sudden rainstorms.

You are missing the point that prolonged periods of drought lower the water table. Even a few days of downpours at a biblical diluvian scale will not replenish this. It can take time to fill those reservoirs and therefore a matter of months not days or even weeks. We have experienced the driest start to the year since 1976 and the driest July since the 1930s,  with some regions witnessing even more extreme conditions than that. We have also had record-breaking levels of demand in places – up 40% or more, which means some companies have had to produce hundreds of millions of litres of extra water each day, equivalent to adding multiple additional town sized provision to the network.

 

Industry has completed a large number of major schemes in recent decades to increase reservoirs, improve the resilience of water supplies and ease pressure on sensitive water sources but our current situation in Europe is unprecedented. That's the era of climate chaos that we are plunging into. Water will not be the only resource that is scarce in some parts of the world and is contended for. 

 

I am reminded though of Dennis Howell who in 1976 was appointed minister of drought whereupon three days later it started raining and as the prolonged and heavy rainfall continued into the Autumn, he became known as the Minister of Floods. 

[MustardTiger]

23 minutes ago, Line-X said:

Air does not 'hold' water. Saying that warm air "holds" more moisture is technically incorrect, but is a common misconception. Saying cold air 'can’t hold as much water vapour as warmer air' is at best a metaphor for observed reality, but It’s a metaphor that can lead people astray in the understanding of meteorology. 

 

Consider a glass of water. Water molecules in liquid are in motion in accordance with varying kinetic energies and consequently different speeds. Some will be slow, others will be faster. The average kinetic energy or if you like 'speed' of the molecules is defined as the temperature of the liquid. Put more energy into the liquid (by heating it for example) and the average speed of the molecules increases. Intermolecular forces in the liquid generally prevent most molecules from escaping, but the most energetic molecules are able to break free from the liquid if they get close to the surface between the liquid and the background medium (gas or vacuum). At this stage the molecules are no longer part of the liquid, but are now existing in the form of water vapour.

Molecules in water vapour also have a wide range of speeds and if the slower molecules strike the surface of the liquid they can be caught and transition from the gaseous phase to the liquid phase. Just like in the liquid, the average speed of the molecules in the water vapour is governed by the temperature.

If we imagine a closed room containing some body of liquid water - say the glass, there will be a constant exchange of water molecules leaving the liquid as water vapour and molecules of water vapour having too low energy to escape the liquid and becoming part of it. Assuming an absence of ventilation or other outside influence, eventually an state of equilibrium is reached between these two directions and the amount of water in each phase remains constant. As with any gas, the water vapour in the room exerts a pressure. The term "partial pressure" refers to the pressure that a component of the gas has if it were the only thing present in a volume. Therefore, at a constant temperature, according to the ideal gas law, this pressure is proportional to the amount of water vapour present. So the partial pressure of the water vapour is a measurement for how much water there is as vapour (per unit of volume).

So in the example of a sealed room hypothetically in a constant state, the exchange between liquid and vapour phase is balanced out, we say that the situation has reached an equilibrium and the the partial pressure of the water vapour in this situation is called the equilibrium vapour pressure. This depends on the temperature of the liquid and of the vapour. With higher temperatures, more molecules in the liquid will have the speed to break free from the liquid and enter the vapour phase and fewer molecules in the vapour will have an energy low enough to be absorbed into the liquid. And vice versa with lower temperatures. So at higher temperatures, the partial pressure of water vapour can be higher. That means that the space - in this case the room - can contain more water vapour. This same space is often also occupied by the air, but it is not the air itself or its properties that determine how much water vapour can be present in the space.

The other important consideration is relative humidity. This is defined as the ratio of the current vapour pressure to the equilibrium vapour pressure. Returning again to the example of a sealed room, the relative humidity will eventually reach 100%. If the relative humidity is less than 100%, then water in liquid form will evaporate at a higher rate than vapour will condense. If there is some form of ventilation, as is the case in most houses, this means that a volume of liquid water will completely evaporate given enough time.

If the relative humidity is above 100%, we speak of supersaturation which is the process that allows clouds to form, expand and increase in mass or aircraft contrails to spread across the sky. The rate of condensation will exceed the rate of evaporation - or more accurately in this case, sublimation, and water will start to condensate through coalescing onto condensation and hygroscopic nuclei. 

The relative humidity depends on the temperature as well as the absolute amount of water present in vapour form, since the equilibrium vapour pressure depends on the temperature. 

Sorry if this seems pedantic - this isn't directed at you. Of grave concern are individuals to whom the public is dependent upon, especially during our current time of climate crisis, who unintentionally misrepresent basic concepts of meteorology. Such as “warm air ‘holds’ more water than cooler air.”  I probably didn't need to type all that - apologies. Simply that in terms of the phase changes I referred to, yes evaporation occurs more frequently at higher temperatures but this had absolutely nothing whatsoever to do with the air being able to ‘hold’ more water because of higher temperatures. Evaporation occurs more frequently when an air parcel is at higher temperatures because very simply the molecules have greater energy and are therefore moving more quickly.

The takeaway from this is the realisation that air has no holding capacity whatsoever. Therefore the claim that warm air “holds more water” than cooler air is completely fallacious. if you hear any source of weather information making this claim, then its purely as a means of easing understanding (incorrectly) and for the purposes of simplification. 

[SpacedX]

Just now, MustardTiger said:

Does your Mum know that you're using her work laptop during your school holiday?...'lol'

[Zear0]

26 minutes ago, Line-X said:

Air does not 'hold' water. Saying that warm air "holds" more moisture is technically incorrect, but is a common misconception. Saying cold air 'can’t hold as much water vapour as warmer air' is at best a metaphor for observed reality, but It’s a metaphor that can lead people astray in the understanding of meteorology. 

 

Consider a glass of water. Water molecules in liquid are in motion in accordance with varying kinetic energies and consequently different speeds. Some will be slow, others will be faster. The average kinetic energy or if you like 'speed' of the molecules is defined as the temperature of the liquid. Put more energy into the liquid (by heating it for example) and the average speed of the molecules increases. Intermolecular forces in the liquid generally prevent most molecules from escaping, but the most energetic molecules are able to break free from the liquid if they get close to the surface between the liquid and the background medium (gas or vacuum). At this stage the molecules are no longer part of the liquid, but are now existing in the form of water vapour.

Molecules in water vapour also have a wide range of speeds and if the slower molecules strike the surface of the liquid they can be caught and transition from the gaseous phase to the liquid phase. Just like in the liquid, the average speed of the molecules in the water vapour is governed by the temperature.

If we imagine a closed room containing some body of liquid water - say the glass, there will be a constant exchange of water molecules leaving the liquid as water vapour and molecules of water vapour having too low energy to escape the liquid and becoming part of it. Assuming an absence of ventilation or other outside influence, eventually an state of equilibrium is reached between these two directions and the amount of water in each phase remains constant. As with any gas, the water vapour in the room exerts a pressure. The term "partial pressure" refers to the pressure that a component of the gas has if it were the only thing present in a volume. Therefore, at a constant temperature, according to the ideal gas law, this pressure is proportional to the amount of water vapour present. So the partial pressure of the water vapour is a measurement for how much water there is as vapour (per unit of volume).

So in the example of a sealed room hypothetically in a constant state, the exchange between liquid and vapour phase is balanced out, we say that the situation has reached an equilibrium and the the partial pressure of the water vapour in this situation is called the equilibrium vapour pressure. This depends on the temperature of the liquid and of the vapour. With higher temperatures, more molecules in the liquid will have the speed to break free from the liquid and enter the vapour phase and fewer molecules in the vapour will have an energy low enough to be absorbed into the liquid. And vice versa with lower temperatures. So at higher temperatures, the partial pressure of water vapour can be higher. That means that the space - in this case the room - can contain more water vapour. This same space is often also occupied by the air, but it is not the air itself or its properties that determine how much water vapour can be present in the space.

The other important consideration is relative humidity. This is defined as the ratio of the current vapour pressure to the equilibrium vapour pressure. Returning again to the example of a sealed room, the relative humidity will eventually reach 100%. If the relative humidity is less than 100%, then water in liquid form will evaporate at a higher rate than vapour will condense. If there is some form of ventilation, as is the case in most houses, this means that a volume of liquid water will completely evaporate given enough time.

If the relative humidity is above 100%, we speak of supersaturation which is the process that allows clouds to form, expand and increase in mass or aircraft contrails to spread across the sky. The rate of condensation will exceed the rate of evaporation - or more accurately in this case, sublimation, and water will start to condensate through coalescing onto condensation and hygroscopic nuclei. 

The relative humidity depends on the temperature as well as the absolute amount of water present in vapour form, since the equilibrium vapour pressure depends on the temperature. 

Sorry if this seems pedantic - this isn't directed at you. Of grave concern are individuals to whom the public is dependent upon, especially during our current time of climate crisis, who unintentionally misrepresent basic concepts of meteorology. Such as “warm air ‘holds’ more water than cooler air.”  I probably didn't need to type all that - apologies. Simply that in terms of the phase changes I referred to, yes evaporation occurs more frequently at higher temperatures but this had absolutely nothing whatsoever to do with the air being able to ‘hold’ more water because of higher temperatures. Evaporation occurs more frequently when an air parcel is at higher temperatures because very simply the molecules have greater energy and are therefore moving more quickly.

The takeaway from this is the realisation that air has no holding capacity whatsoever. Therefore the claim that warm air “holds more water” than cooler air is completely fallacious. if you hear any source of weather information making this claim, then its purely as a means of easing understanding (incorrectly) and for the purposes of simplification. 

Not touched thermodynamics in many a year, but doesn't hotter air have a higher dew point and therefore higher saturation point making it more humid and hold more water vapour? This is the engineers view, not the meteorologists! 

[SpacedX]

17 minutes ago, Zear0 said:

Not touched thermodynamics in many a year, but doesn't hotter air have a higher dew point and therefore higher saturation point making it more humid and hold more water vapour? This is the engineers view, not the meteorologists! 

The amount of water that air is said to accommodate depends on temperature yes. The absolute humidity then is defined as the percentage of water to air and decreases when the temperature decreases. The relative humidity is the ratio between the current and the maximum humidity, which increases with decreasing temperature. As you know, the temperature at which the relative humidity reaches 100% is called the dew point. Actually, I think the latter is the more useful term here. The higher the dew point rises, the greater the amount of moisture in the air and as such is a better gauge than humidity in terms of comfort. In fact, relative humidity can be misleading. For example, a temperature of 30 and a dew point of 30 will give you a relative humidity of 100%, but a temperature of 80 and a dew point of 60 produces a relative humidity of 50%. It would feel much more "humid" on the 80 degree day with 50% relative humidity than on the 30 degree day with a 100% relative humidity - as a consequence of the higher dew point.

 

BUT for a substance to be a gas, the kinetic energy of the molecules that make it up must be higher than the electrostatic potential energies that hold it together. When we talk about air "holding" water we are really talking about the amount of water that would be in the vapour phase relative to the amount that would be liquid at equilibrium - hence my rather unnecessary essay. As an engineer, you'll view temperature as a measure of the average kinetic energy of molecules. So, as the temperature increases, the fraction of water that can exist as vapour increases. Since air is already a gas under any conditions where water vapour can exist, ostensibly the air "holds" more water as temperature increases. But 'holds' is an erroneous term. Air does not "hold" water. Warm air often has more water molecules than cooler air but this is because of the energy level of the water particles The dew point is then the temperature to which air must be cooled to become saturated with the available water vapour.

Edited 11 August 2022 by Line-X

[yorkie1999]

it's days like these that everyone in the uk looks forward to, and all we do is moan when we get them.

[Zear0]

4 minutes ago, yorkie1999 said:

it's days like these that everyone in the uk looks forward to, and all we do is moan when we get them.

Some of us are happiest when we're moaning. 

[Innovindil]

4 minutes ago, yorkie1999 said:

it's days like these that everyone in the uk looks forward to, and all we do is moan when we get them.

Anyone that looks forward to days like today should be sent to Rwanda.

 

Pure filthy weather. Fine if chilling on the beach, shite if you're going about a normal work day.

[Parafox]

10 minutes ago, yorkie1999 said:

it's days like these that everyone in the uk looks forward to, and all we do is moan when we get them.

Yes to the opening sentence but I think that's a generational thing but I think the concern now is the effect on food production and the difficulties encountered when there's a prolonged period of excessive heat, rather than complaining about the heat. I agree, people do go "ooh, it's just too hot", and I agree, it's uncomfortable particularly in cities and central areas away from the coast. But there are bigger things to be concerned about with the world's climate. 

I for one, am not looking forward to 30-40 deg summers every year

Edited 11 August 2022 by Parafox

[Parafox]

4 minutes ago, Zear0 said:

Some of us are happiest when we're moaning. 

True. You only have to read the match day threads. Or any thread relating to BR or the team.

[yorkie1999]

51 minutes ago, Parafox said:

Yes to the opening sentence but I think that's a generational thing but I think the concern now is the effect on food production and the difficulties encountered when there's a prolonged period of excessive heat, rather than complaining about the heat. I agree, people do go "ooh, it's just too hot", and I agree, it's uncomfortable particularly in cities and central areas away from the coast. But there are bigger things to be concerned about with the world's climate. 

I for one, am not looking forward to 30-40 deg summers every year

i'm looking forward to growing water melons and pomegranates in the back garden

[Unabomber]

1 hour ago, yorkie1999 said:

it's days like these that everyone in the uk looks forward to, and all we do is moan when we get them.

Why would we look forward to this? No air conditioning, working in the heat, can’t sleep etc. I like nice weather but there is a limit to what is genuinely enjoyable in this country. 

[grobyfox1990]

1 hour ago, Innovindil said:

Anyone that looks forward to days like today should be sent to Rwanda.

 

Pure filthy weather. Fine if chilling on the beach, shite if you're going about a normal work day.

I’ve been to Rwanda and it was much colder than this! Been loving this period, genuine heat. Essentially been outside all day everyday since Monday. Beautiful. Although my laptop is nearly fried 

[Foxdiamond]

I too am not looking forward for summers at over 30c with so little rain. Climate change should be a worry for us all. Never understood why anyone would prefer such high temperatures to say 20c to 25c with some rainy days. So much for a green and pleasant land. When the weather is the story it is seldom a good thing

[walkerleeds]

4 hours ago, Greg2607 said:

https://www.thelocal.fr/20220811/in-pictures-french-drought-intensifies-loire-dries-up/

 

people really do need to wake up.... 

 

Beavers are part of the solution.... hopefully they quickly establish in the UK. 

 

Wow. I  styed near the Loire last month and visited it a few times. So much wildlife will be suffering as a result of this. 

Edited 11 August 2022 by walkerleeds

[Trumpet]

I can’t wait to walk the dogs mid October in 15c pissing down rain. I love hot weather, but not if I have to live in it without a pool, cold beer and air con to retreat to.

[fox_favourite]

1 minute ago, Trumpet said:

I can’t wait to walk the dogs mid October in 15c pissing down rain. I love hot weather, but not if I have to live in it without a pool, cold beer and air con to retreat to.

That’s the issue, there’s no rest bite from the heat. Which in turn leaves me feeling tired and drained all the time. Health implications as well for some people is massive. Farmers are affected, dry crops, wild fires to contend with which will have implications further down the road. 
 

On a personal level, I can’t wait for the cooler days. I love the spring myself.
 

 

[Paninistickers]

12 minutes ago, Trumpet said:

I can’t wait to walk the dogs mid October in 15c pissing down rain. I love hot weather, but not if I have to live in it without a pool, cold beer and air con to retreat to.

I wouldn't even bank on that. On the 16 years or so I have had kids, i used to wrap up on Halloween night. I've noticed the last 4 or 5 years Halloween has had temperatures around 16 - 19 degrees and we walk around in virtual summer wears.

 

Autumn doesn't seem to exist. We seem.to go from Indian summer straight to winter.now

[Foxdiamond]

16 minutes ago, Paninistickers said:

I wouldn't even bank on that. On the 16 years or so I have had kids, i used to wrap up on Halloween night. I've noticed the last 4 or 5 years Halloween has had temperatures around 16 - 19 degrees and we walk around in virtual summer wears.

 

Autumn doesn't seem to exist. We seem.to go from Indian summer straight to winter.now

Yes, not good

[SpacedX]

35 minutes ago, Trumpet said:

I can’t wait to walk the dogs mid October in 15c pissing down rain. I love hot weather, but not if I have to live in it without a pool, cold beer and air con to retreat to.

That in itself is a huge concern because climate change is set to drive this up fourfold in the next few decades.