You are one of the finest teachers. I normally have problem paying attention but your lecture kept me engaged and cleared up so many confusions. May Allah bless you.
You are a ridiculously good teacher. I am a uni teacher myself and I wish I could be this clear to explain mass spectrometry to my students haha! Thanks for the amazing meteo course
I love this lecture series so much! I've always loved clouds/storms/weather and it's so cool to start to understand. Developing the lectures to spend time on common mistakes is so helpful. The humor and cats are total bonuses as well 🥰
That was so interesting about relative humidity. The way I will think of it now when I see that percentage is that the higher the number the closer we are to getting dew!
Thanks. The real correct answer at 35:15 not given because misplaced professional decorum is not enough information because it depends on how sweaty the students are (age dependent) and how many 630 ml bottles of energy drink the little tykes are relentlessly consuming.
Hi Mel, I'm one of those folks stuck at home due to the virus. I'd decided to spend the time teaching myself a bit about earth system science and found your lecture on clouds (and how to abduct a donkey). The result of which is I'm now ploughing through your short course on understanding the weather. Fascinating stuff. We don't get too many monsoons here on the UK east coast but we certainly get dew! And we don't have to worry much about the heat index either, the wind chill factor is more of an issue! Anyhow in between decorating the house and getting out once a day for some exercise and to check on what the weathers doing I'm plugging into your lectures. Thanks for making them available. BTW is that Zebra now glowing in the dark!!
Thanks for your message Stephen! I'm always glad to hear from people who are finding any of these lectures useful. If you get bored I do have some problem sets on my website regarding humidity if you want to try them. Some of them are more like thought problems, but I made them so people can really assess whether they understand humidity or not. Cheers!
At 7:59 if one were to ask: The dew point of the air is 54F. The temperature outside is 75F. The air temperature increases and warms to 80F How has the dew point changed? Check my thought process here. I’ll start by stating that cold air “holds” less water and warm air “holds” more water. Since the temperature has increased the air can now “hold” more water. Dew Point is the temperature at which air becomes saturated. Therefore, the Dew point has increased as the air can now hold more water than before. Why is this incorrect?
If the Dew Point is 54F, then that tells us that saturation will occur at 54. If I raise the temperature to 90F, it doesn't change the fact that I have to cool it back down to 54 for condensation to occur. At 90F, we could certainly put more water into the air, but unless more water is added in somehow, the dew point stays the same.
@@MelStrong @Mel Strong follow up question. Doest it requires dew drop to form when we are talking about dew point? I get the part about mixing ratio states that aslong as we don't reach saturation condensation won't occur there for no dew. If there's not enough moisture even if we reach dew point, dew will not form. I mean in lecture 2 if I remember correctly if the temperature increases dew point also increases and opposite if cooled.
So well explained .vry easy to understand. Pls do more videos on type of winds:Geostrophic wind ,coriolis force, Gradient wind etc And Stability and instability of atmosphere like DALR,ELR ,SALR etc.🙏
At 3:40, I would say not enough information to answer: if there was _any_ liquid water present (and there usually is), raising the temperature would increase evaporation and thus increase the mixing ratio. At 5:00, again it's not enough information: if the air is already saturated, enough water will condense on the coolest available surface to offset the amount added by the pot of boiling water.
Hi, Mel. First off, thank you for providing clear explanations for all these topics. I've watched your previous two presentations and I'm pleasantly surprised by the accessibility of their content. However, I might have misunderstood some details and I hope you could clarify. In this presentation's intro you say that adding/removing water from the air changes the mixing ratio, which is pretty straight-forward. You also state that it also changes the dew point. That gives me some trouble, as I was under the impression that, for a given (constant) pressure, dew point is only influenced by temperature and doesn't depend on the actual vapor content of the gas. Did I get anything wrong? Also, you asked if cooling a room from 75F to 40F when dew point is 54F would saturate the air. Actually, in my opinion, there's not enough info to answer this question because we don't know how much actual water was in the air to begin with (initial mixing ratio), because if the air was dry enough at the start, the mixing ratio could be still well below the maximum m.r. at 40F. Therefore, there might not be enough vapor in the air to condense even at 40F. Simply cooling the air below the dew point does not necessarily mean there's actual water in the air to form dew, which is a point you clearly made in Lecture 2. Thanks again!
The dew point absolutely tells you how much water is in the air. The more water molecules in the air, the higher the dew point. The less water molecules in the air, the lower the dew point. Although I don't cover it, there is a mathematical way one can convert dew point into mixing ratio and get a concrete number that can be more easily visualized. Dew point is NOT influenced by temperature unless the air gets so cold that condensation starts to occur. If the dew point is 54F, then we know that once the temperature drops down to 54, the air is saturated. Any more further cooling will start removing water from the air by condensation. As condensation happens, the dew point lowers as well. If you haven't discovered it yet, there is an 'extra' lecture on this that follows where I do more examples with some animated thermometers. That might also help you. You can find it within my playlist of lectures - should be right after this one.
I am unsure how on around 34:00 it says Cold Day + high RH = feels colder, but the heat index states the opposite, sure 70°F isn't cold, but with high RH it feels slightly warmer or the same. Does that change with low temp since the saturation point is far lower, therefore it feels like you are more wet (feeling colder)?
Hi Mel Strong, I am a homeschool student, and I have been really enjoying your lectures. I have a question for you regarding the dew point: If the air has reached it dew point with RH 100%, does condensation necessarily have to occur? Since we are not adding any more water vapor to the air, nor cooling the temperature further, wouldn't the air just stay saturated, but without the formation of dew?
Hi Megan. So if we cool the air just until the RH reaches 100% and then stop, we wouldn't necessarily see any visible dew. At 100%RH, water molecules are moving back and forth between liquid droplets and vapor. But, at that point, the droplets are microscopic. To get large drops, we would need to cool the air further to produce more condensation. If the air is cooler than the ground, then the result would be a mist of microscopic drops (fog). Technically speaking there would be a point when we could get to 99.999% RH and theoretically we would have no liquid drops anywhere - but this is hard to do in nature as the air is not well mixed and the temperatures are not the same everywhere. Usually the ground is the first to cool, with the thin surfaces cooling the fastest. So in reality you have these thin surfaces (like grass) where the air right next to the grass is being cooled below its dew point and the RH is 100%. But then just a short distance above the grass the air is not yet saturated because the temperature up there isn't cool enough yet. So the true process is more complicated than I am making it out to be.
Yes but no, If there is any water source available in the room, the water will vaporate more, there will be more water vapor and that means higher mixing point thus higher dew point. But that kind of information is not giving so it stays the same.
The conditions where rain forms up in the sky are different than those at the surface. When precipitation is forming in the cloud, Temperature = Dew Point and RH is 100% (actually it can be supersaturated but I don't cover that in any of my lectures). Then the rain falls down into the lower atmosphere where it is dryer. So that is why it can be raining when the RH is not 100% at the surface. If it rains for long enough, eventually the air at the surface will become saturated and RH will become 100%.
Came here to learn how to identify clouds and what each type means... now I'm jumping into lecture 4 all intrigued and happy.
LOL two of us
It's weird how much fun these lectures are for me.
same to me , its easy to understand the concepts with him, i like him so much
The presence of the cat makes me trust you with my life
I am a 70+ male who's stumbled across this site . loving exercising my gray cells!
You are one of the finest teachers. I normally have problem paying attention but your lecture kept me engaged and cleared up so many confusions. May Allah bless you.
Mate all these videos are so quality. Thank you so much for what you're doing. You're very good at it.
Thanks - hope you got something out of them.
You are a ridiculously good teacher. I am a uni teacher myself and I wish I could be this clear to explain mass spectrometry to my students haha! Thanks for the amazing meteo course
I love this lecture series so much! I've always loved clouds/storms/weather and it's so cool to start to understand. Developing the lectures to spend time on common mistakes is so helpful. The humor and cats are total bonuses as well 🥰
This is the best course I have seen on clouds etc. I am really enjoying it! Thank you. Jenni
your lectures are total gems!
That was so interesting about relative humidity. The way I will think of it now when I see that percentage is that the higher the number the closer we are to getting dew!
These are really excellent lectures-thanks for putting them on UA-cam! Such a clear explanation of this confusing subject.
Thanks. The real correct answer at 35:15 not given because misplaced professional decorum is not enough information because it depends on how sweaty the students are (age dependent) and how many 630 ml bottles of energy drink the little tykes are relentlessly consuming.
Sire you're great. You answered everything that was on my mind 🙂
Hi Mel, I'm one of those folks stuck at home due to the virus. I'd decided to spend the time teaching myself a bit about earth system science and found your lecture on clouds (and how to abduct a donkey). The result of which is I'm now ploughing through your short course on understanding the weather. Fascinating stuff. We don't get too many monsoons here on the UK east coast but we certainly get dew! And we don't have to worry much about the heat index either, the wind chill factor is more of an issue! Anyhow in between decorating the house and getting out once a day for some exercise and to check on what the weathers doing I'm plugging into your lectures. Thanks for making them available. BTW is that Zebra now glowing in the dark!!
Thanks for your message Stephen! I'm always glad to hear from people who are finding any of these lectures useful. If you get bored I do have some problem sets on my website regarding humidity if you want to try them. Some of them are more like thought problems, but I made them so people can really assess whether they understand humidity or not. Cheers!
All your videos are amazing and informational! and you have made it very entertaining as well! Thanks a lot!
Amazing content! I wish my teachers had this kind of skill to explain things. Thanks a lot. 🚀
Thank you for the video. Your cat is so cute!!
I knew you were a geologist !! Thank you for the video, they are great.
Your videos are brilliant 👍
Thank you very much, i really enjoyed it!! :D
Thanks for your awesome presentation 👍👍
At 7:59 if one were to ask:
The dew point of the air is 54F. The temperature outside is 75F. The air temperature increases and warms to 80F How has the dew point changed?
Check my thought process here. I’ll start by stating that cold air “holds” less water and warm air “holds” more water. Since the temperature has increased the air can now “hold” more water. Dew Point is the temperature at which air becomes saturated. Therefore, the Dew point has increased as the air can now hold more water than before.
Why is this incorrect?
If the Dew Point is 54F, then that tells us that saturation will occur at 54. If I raise the temperature to 90F, it doesn't change the fact that I have to cool it back down to 54 for condensation to occur. At 90F, we could certainly put more water into the air, but unless more water is added in somehow, the dew point stays the same.
@@MelStrong @Mel Strong follow up question. Doest it requires dew drop to form when we are talking about dew point?
I get the part about mixing ratio states that aslong as we don't reach saturation condensation won't occur there for no dew. If there's not enough moisture even if we reach dew point, dew will not form.
I mean in lecture 2 if I remember correctly if the temperature increases dew point also increases and opposite if cooled.
Never mind I've read your other comments now it make sense.
So well explained .vry easy to understand.
Pls do more videos on type of winds:Geostrophic wind ,coriolis force, Gradient wind etc
And
Stability and instability of atmosphere like DALR,ELR ,SALR etc.🙏
At 3:40, I would say not enough information to answer: if there was _any_ liquid water present (and there usually is), raising the temperature would increase evaporation and thus increase the mixing ratio. At 5:00, again it's not enough information: if the air is already saturated, enough water will condense on the coolest available surface to offset the amount added by the pot of boiling water.
I bet you're a mathematician XD
Excellent lectures! How do we measure the mixing ratio?
Hi, Mel. First off, thank you for providing clear explanations for all these topics. I've watched your previous two presentations and I'm pleasantly surprised by the accessibility of their content.
However, I might have misunderstood some details and I hope you could clarify.
In this presentation's intro you say that adding/removing water from the air changes the mixing ratio, which is pretty straight-forward. You also state that it also changes the dew point. That gives me some trouble, as I was under the impression that, for a given (constant) pressure, dew point is only influenced by temperature and doesn't depend on the actual vapor content of the gas. Did I get anything wrong?
Also, you asked if cooling a room from 75F to 40F when dew point is 54F would saturate the air. Actually, in my opinion, there's not enough info to answer this question because we don't know how much actual water was in the air to begin with (initial mixing ratio), because if the air was dry enough at the start, the mixing ratio could be still well below the maximum m.r. at 40F. Therefore, there might not be enough vapor in the air to condense even at 40F. Simply cooling the air below the dew point does not necessarily mean there's actual water in the air to form dew, which is a point you clearly made in Lecture 2.
Thanks again!
The dew point absolutely tells you how much water is in the air. The more water molecules in the air, the higher the dew point. The less water molecules in the air, the lower the dew point. Although I don't cover it, there is a mathematical way one can convert dew point into mixing ratio and get a concrete number that can be more easily visualized. Dew point is NOT influenced by temperature unless the air gets so cold that condensation starts to occur. If the dew point is 54F, then we know that once the temperature drops down to 54, the air is saturated. Any more further cooling will start removing water from the air by condensation. As condensation happens, the dew point lowers as well. If you haven't discovered it yet, there is an 'extra' lecture on this that follows where I do more examples with some animated thermometers. That might also help you. You can find it within my playlist of lectures - should be right after this one.
Off topic, those are some of the nices thumb nail beds I have see.
I am unsure how on around 34:00 it says Cold Day + high RH = feels colder, but the heat index states the opposite, sure 70°F isn't cold, but with high RH it feels slightly warmer or the same. Does that change with low temp since the saturation point is far lower, therefore it feels like you are more wet (feeling colder)?
I'm going to DEW that calculation...pun intended...
Hi Mel Strong, I am a homeschool student, and I have been really enjoying your lectures. I have a question for you regarding the dew point: If the air has reached it dew point with RH 100%, does condensation necessarily have to occur? Since we are not adding any more water vapor to the air, nor cooling the temperature further, wouldn't the air just stay saturated, but without the formation of dew?
Hi Megan. So if we cool the air just until the RH reaches 100% and then stop, we wouldn't necessarily see any visible dew. At 100%RH, water molecules are moving back and forth between liquid droplets and vapor. But, at that point, the droplets are microscopic. To get large drops, we would need to cool the air further to produce more condensation. If the air is cooler than the ground, then the result would be a mist of microscopic drops (fog). Technically speaking there would be a point when we could get to 99.999% RH and theoretically we would have no liquid drops anywhere - but this is hard to do in nature as the air is not well mixed and the temperatures are not the same everywhere. Usually the ground is the first to cool, with the thin surfaces cooling the fastest. So in reality you have these thin surfaces (like grass) where the air right next to the grass is being cooled below its dew point and the RH is 100%. But then just a short distance above the grass the air is not yet saturated because the temperature up there isn't cool enough yet. So the true process is more complicated than I am making it out to be.
@@MelStrong Thanks for taking the time to write out this great answer for me. This helps clear up my question, as did your lecture on evaporation.
Thanks for these videos! Do you explain air stability and instability on your next lectures?
Stability and instability are covered in lecture 5 I believe, though not in a strictly quantitative sense.
I love the big Fatty Lumpkins cat!! I bet his name is Cumulonimbus.
Can't you also do the sew point divided air temp for relative humidity?
7:32, we increase temperature in the room, dew point should go eventurally higher with higher temperature?
Yes but no, If there is any water source available in the room, the water will vaporate more, there will be more water vapor and that means higher mixing point thus higher dew point. But that kind of information is not giving so it stays the same.
Why is it raining right now in Naperville, IL when the RH is 86%, the temperature is 75 and DP is 70F?
Thanks
The conditions where rain forms up in the sky are different than those at the surface. When precipitation is forming in the cloud, Temperature = Dew Point and RH is 100% (actually it can be supersaturated but I don't cover that in any of my lectures). Then the rain falls down into the lower atmosphere where it is dryer. So that is why it can be raining when the RH is not 100% at the surface. If it rains for long enough, eventually the air at the surface will become saturated and RH will become 100%.
The cat looks like a cloud 😊
good vid bru.
you wasted your time to come down here
Relative humidity is such a terrible name. Just call it saturation, duh