Lecture 3: Introduction to relative humidity

In this lecture I cover relative humidity and the temperature effects on different humidity variables.

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.

[TradSarah]

Came here to learn how to identify clouds and what each type means... now I'm jumping into lecture 4 all intrigued and happy.

[Labroidas]

It's weird how much fun these lectures are for me.

[davidfield]

I am a 70+ male who's stumbled across this site . loving exercising my gray cells!

[userNULL]

The presence of the cat makes me trust you with my life

[juliabauza-martinez]

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

[iReece]

Mate all these videos are so quality. Thank you so much for what you're doing. You're very good at it.

[neelamkhan]

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.

[therync]

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 🥰

[debbiet]

These are really excellent lectures—thanks for putting them on YouTube! Such a clear explanation of this confusing subject.

[VegaPhil]

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!

[jennimartin]

This is the best course I have seen on clouds etc. I am really enjoying it! Thank you. Jenni

[stephensmith]

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!!

[EcoresolveInc]

All your videos are amazing and informational! and you have made it very entertaining as well! Thanks a lot!

[adityanathbhattacharya]

Sire you're great. You answered everything that was on my mind 🙂

[RaphaelNussbaum]

Amazing content! I wish my teachers had this kind of skill to explain things. Thanks a lot. 🚀

[guilhem]

I knew you were a geologist !! Thank you for the video, they are great.

[hugbearsx]

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!

[mariano_buitrago]

Excellent lectures! How do we measure the mixing ratio?

[푸딩-ok]

Thank you for the video. Your cat is so cute!!

[grindupBaker]

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.