Lecture 4: Introduction to evaporation and latent heat

UPDATE: I'm making materials available for all of my lectures on my website (melstrong.org) for either those bored folks stuck at home due to the virus or teachers looking for online content. For this lecture I have an experiment that you might be able to conduct at home, plus some written questions regarding evaporation and latent heat. With answer key.
This was originally part of the Blue Planet lecture series at the University of New Mexico. If you are interested in weather, this lecture is now part of my "weather short course" playlist, where there are another ~15 videos similar to this one.

Пікірлер: 56

  • @po1ly414
    @po1ly4149 ай бұрын

    I am a pilot and these weather courses are so incredibly useful. You are helping far more people in many more ways than you may know

  • @hyperelliptik
    @hyperelliptik Жыл бұрын

    These lectures are helping me *a lot* with studying for a basic meteorology/weather exam I've had a grand total of 2 days to prepare for. You explain things so intuitively, never skipping over a subject or concept thinking the listener is already familiar with it, and you repeat things over and over and don't make them sound more complicated than they have to be. It takes the pressure off from trying to _memorize_ each term just for the sake of passing the exam, and instead focuses on the conceptual understanding of what's actually going on which is a much better way to study imo... This is a great way to teach (and to learn!), so thank you for being so good at it haha.

  • @caiodollis6159
    @caiodollis61594 жыл бұрын

    I'm from Brazil and I fully understand what you say. You speak so clear! Thank you for the classes, I'm understanding much better the world around me

  • @MelStrong

    @MelStrong

    4 жыл бұрын

    Thanks I'm glad you are getting something out of these!

  • @annabranco5152
    @annabranco51529 ай бұрын

    This is be best and clearer explanation I’ve even had about latent heat. THANK YOU!!!

  • @safirahmed2946
    @safirahmed2946 Жыл бұрын

    Mel Strong you have been blessing for me, such a clear basics concepts for climate change student. Thank You!

  • @aerosol_
    @aerosol_ Жыл бұрын

    I'm hooked with these videos. I understand more of the weather in general thanks to your intuitively video classes. It has even made me understand why the raining days, clouds and the sun has not come out for a few days when planning outdoor activities and, not to take it by bad luck. Thanks for sharing this weather knowledge sir.

  • @Jatodd93
    @Jatodd93 Жыл бұрын

    Thank you a million times over! Truly. You are a very clear explainer/speaker.

  • @liberteegalitefraternite7804
    @liberteegalitefraternite7804 Жыл бұрын

    I am amazed by the way You explain it, Thank You so much

  • @clo-1588
    @clo-15882 жыл бұрын

    Hi! I just want to let you know that I have been LOVING your videos. This is not my field but I am very intrigued by weather and the skies and nature around me and I have found most material to be dry and not exactly what I want to watch or read after a day of work, but your videos check every box for me. You are an incredible teacher, straight to the point yet providing enough pertinent examples for understanding, your tech setup is ideal (video, image, sound, etc), and of course, your lovely cats make me immensely happy :) Thank you for sharing this with people like me, who otherwise might not get to learn about all of these wonderful things!

  • @MelStrong

    @MelStrong

    2 жыл бұрын

    Thank you very much! I really appreciate that you took the time to write such a long comment. It is very nice for me to read after a hard day! The kitties send their love...

  • @clo-1588

    @clo-1588

    2 жыл бұрын

    Glad you enjoyed my comment!!! It is nice to get feedback, I get it. I am currently in my end-of-semester at school in something else but I am devouring these in my free time. I have been sharing snippets with my friends, too - things I find very cool, or bits that made me laugh. They are enjoying the cats as well :)

  • @janinedupreez2714

    @janinedupreez2714

    Жыл бұрын

    Wow! Im really enjoying your videos Mel. Im 53 and learning about the weather. Your explanations make the science easier to understand and you are a natural born teacher. Thank you for enriching the world with your knowledge.

  • @IWFRAY
    @IWFRAY2 жыл бұрын

    I live in central Arabia, one the driest areas in the world where RH in summer in 10-20% range, evaporative coolars are working very good especially if mixed with AC (you cannot rely on evaporative cooler only if temperature around 48 C or 122 F) Sometimes we get humid weather in the middle of summer, I can tell that the weather outside is humid when I notice the evaporative cooler is barely cooling. Thank you professor Mel for your intereting lectures

  • @jiwonkim4794
    @jiwonkim47942 жыл бұрын

    Beautifully well explained!!! 😆

  • @firstimemama2010
    @firstimemama20104 жыл бұрын

    I'm so glad I found your video about weather! Your a great teacher and I look forward to learning more. Thanks for taking the time to make these. Its much appreciated Mel!

  • @MelStrong

    @MelStrong

    4 жыл бұрын

    Thanks I hope you are learning something. Almost nobody watches this one...I guess latent heat sounds boring to people...

  • @HypoxicWaiter
    @HypoxicWaiter Жыл бұрын

    Hello from rainy England! For the last two years I've been studying for the 13 professional flying exams and now just have two subjects left, Meteorology and General Navigation. I must have watched hundreds of different educational youtube creators over the last 24 months but none come close to the standard of your videos Mel. They are so so good, and I think thats an understatement. Thankyou!

  • @briandwi2504
    @briandwi25046 ай бұрын

    Very informative and interesting, thanks!

  • @papacowboy
    @papacowboy2 жыл бұрын

    Love this lecture series! Down south of Abilene Tx we used evaporative coolers in our farm house- worked very well here too, and easier on electricity and environment. I grew up near the gulf, doubt it would work there. Even a/c units had a tough time there.

  • @MelStrong

    @MelStrong

    2 жыл бұрын

    I'm quite surprised they would have worked at all in Abilene!

  • @user-go8pj7bo8r
    @user-go8pj7bo8r9 ай бұрын

    Great series of info. THANKS! Swamps cooler are used in the part of the country were there are no actual swamps - Have to laugh at the English language.

  • @vivfouracre5695
    @vivfouracre56953 жыл бұрын

    Your lectures are wonderful, at last I am beginning to understand the weather. Thank you

  • @MelStrong

    @MelStrong

    3 жыл бұрын

    Thank you glad they are helpful!

  • @kimmjones2202
    @kimmjones2202 Жыл бұрын

    Thank you Sir, Very well explained.

  • @janeycole3327
    @janeycole33272 ай бұрын

    Australians used to have a device called the Coolgardie safe which used the same principle as the swamp cooler. A wooden box with hessian or burlap layers that were kept wet. Evaporation cooled the box and your meat, butter and the like would stay cool. Good 'ealth, John Warner. Australia

  • @alkei_i_am
    @alkei_i_am4 ай бұрын

    Amazing lectures,greetings from Belarus

  • @EcoresolveInc
    @EcoresolveInc3 жыл бұрын

    Binge-watching your videos for acing my qualifier exams! Thanks a ton!

  • @MelStrong

    @MelStrong

    3 жыл бұрын

    If you failed....I refuse to be held accountable....LOL

  • @EcoresolveInc

    @EcoresolveInc

    3 жыл бұрын

    @@MelStrong hahahahha :D

  • @luisaevelinschubert8668
    @luisaevelinschubert86683 жыл бұрын

    The cat makes me want to learn it all... best teaching!

  • @AF_CSL
    @AF_CSLАй бұрын

    Great explanation! Thanks 🙏

  • @sagaedling195
    @sagaedling195 Жыл бұрын

    I have an exam tomorrow on weather and climate. I haven’t studied enough and today the anxiety is high. This playlist is very good, I understand things I hadn’t before and it’s good to take it all from the beginning. Probably going to have to re-do the exam after Christmas, so this will probably be my December playlist 😅 I’m doing a candidate in biology, which includes some geology courses and I’m sooo lost.

  • @joshntn37111

    @joshntn37111

    Жыл бұрын

    Are you sure it's anxiety? Being nervous before a big exam is normal. I'm generally curious how the majority of humans suffer from anxiety now. 30 years ago it's was just referred to as being "nervous" about something or other and it helped us grow by facing these challenges. Saying you have "anxiety" seems like a trend and it's cool to say you suffer from something. All I am saying is that you are a lot stronger than you think you are. It's all in your head. You are not a victim. No more crying about it. Stay strong push through it and you will be proud of yourself later. Good luck to you.

  • @sagaedling195

    @sagaedling195

    Жыл бұрын

    @@joshntn37111 it sounds like you are blessed with a life without much anxiety, which is a good thing. There is a big difference between nervousness and anxiety, and I know it well. I mean anxiety when I say it, and I’m not going to go into more detail than that about my mental health with a stranger on the internet.

  • @PhysicsYogi24
    @PhysicsYogi244 жыл бұрын

    Beautiful explanation brother 😍😍😍

  • @narayanprasad7933
    @narayanprasad79334 жыл бұрын

    nice work buddy. keep it up

  • @MrManou1973
    @MrManou19732 жыл бұрын

    Great lecture! Thanks

  • @abhaysify
    @abhaysify3 жыл бұрын

    Nice and wonderful explanation..

  • @abdelz1617
    @abdelz16173 жыл бұрын

    Thank you so much, you are great!

  • @independentsparrow4825
    @independentsparrow48252 жыл бұрын

    Now after I watched this video I understood why ice has less density than liquid water. Because in ice the molecules has less vibration but have high distance between each other than liquid water.

  • @MelStrong

    @MelStrong

    2 жыл бұрын

    Yes the crystalline structure of ice has more 'open space' than the liquid

  • @abcd-nn9pk
    @abcd-nn9pk15 күн бұрын

    really love it

  • @ronaldgarrison8478
    @ronaldgarrison84782 жыл бұрын

    For deciding where to use evaporative coolers, the best map would be one that weights humidity toward the warmest days. However, at the same time, I would not expect that distinction to significantly change the threshold of decision.

  • @aemorari
    @aemorari2 жыл бұрын

    NIIIIIIIIIICE STUFF... THANKS

  • @MelStrong

    @MelStrong

    2 жыл бұрын

    Thaaaaaaanks

  • @ronaldgarrison8478
    @ronaldgarrison84782 жыл бұрын

    This presentation made me think about something I never considered before. Suppose you have a cup of water sitting outside, and the relative humidity is exactly 100%. There will be no net evaporation at all. Does that mean that cup of water will just sit there forever, and the amount in the cup will never change? I don't think so. That would be too neat. Water molecules will be constantly escaping from the cup, and others will be condensing into the cup. As many molecules must condense as there are evaporating. But I don't think the condensation will all be into the cup. Gradually, the cup will lose water, but there will be condensation around the cup. I expect the cup to eventually be empty, and there will be a pattern of condensation around the cup. The condensed water will eventually spread more and more, as time goes on, until no drops can be detected anywhere, because the water has spread too widely. But just how this proceeds will be governed by some physics that could get quite complex. Does anyone have a quantitative analysis of this kind of thing?

  • @MelStrong

    @MelStrong

    2 жыл бұрын

    A cup of water at 100%RH will not evaporate, but there will be constant exchange of water molecules with the atmosphere. If you had a way of labeling each water molecule in your cup, you would notice that over time your original water molecules have been leaving and new ones have joined. This type of experiment can be done with stable isotopes, where the isotopic composition of water in the cup starts out different than the composition of the water vapor in the atmosphere. Over time the isotopic composition in the cup will approach that of the atmosphere. The rate at which this happens depends on temperature.

  • @ronaldgarrison8478

    @ronaldgarrison8478

    2 жыл бұрын

    @@MelStrong I still say the water in the cup would slowly disperse over the surrounding environment, just due to entropy. If all the water in the cup were to stay the same forever, I think I'd consider that as evidence that maybe I really am living in a simulation.

  • @user-zp1ec3ot7g
    @user-zp1ec3ot7g2 ай бұрын

    What is the difference when dew is formed and fog is formed?

  • @ykhan66
    @ykhan663 жыл бұрын

    Sorry, maybe i am not fully connecting the dots, but why is relative humidity correlated with the evaporation rate?

  • @MelStrong

    @MelStrong

    3 жыл бұрын

    At 100% relative humidity, each water molecule that enters the air must be balanced with one molecule that is removed from the air - because the air is at saturation. So a puddle of water that sits in air of 100% RH will never evaporate. At the extreme opposite, if you had a puddle of water sitting in air of 1% RH, there would be a huge flux of water molecules leaving compared to those entering, and the puddle would be evaporating rapidly.

  • @yassarghanimi1863
    @yassarghanimi1863 Жыл бұрын

    Thanks again for these excellent lectures! Four decades ago I had learnt thermodynamics at universty. I wish, I have had a professor like you at that time. Now I am learning just for fun and not to get my graduation. 👨🏼‍🎓

  • @fangugel3812
    @fangugel38124 ай бұрын

    So no concept of thermodynamics for students at this level? Unfortunate.

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