Why Does Humidity Make It Feel Hotter?
Summary
TLDRThis script delves into the complexities of weather forecasting, emphasizing that temperature isn't the sole indicator of how hot it feels outside. It explains how humidity affects our perception of heat, with sweat not evaporating efficiently in high humidity, leading to a hotter and more uncomfortable feeling. The script clarifies the limitations of relative humidity in predicting comfort levels and introduces the dew point as a more accurate measure. It suggests that a dew point above 18 degrees is when it starts to feel 'sticky and gross,' advising viewers to seek air-conditioned environments on such days.
Takeaways
- đĄïž Temperature alone isn't the best indicator of how hot or cold it feels outside.
- đ§ Humidity plays a significant role in how our bodies perceive heat because it affects sweat evaporation.
- đ„ When it's humid, sweat doesn't evaporate as quickly, causing us to retain heat and feel hotter and damp.
- đŹïž Relative humidity measures how close the air is to being saturated with water vapor, but it's not the best indicator of how hot it feels.
- đĄïž The saturation point of air increases with temperature, meaning the same relative humidity can feel different on hotter days.
- đ The dew point is a more useful measure of how muggy it feels outside, as it indicates the amount of moisture in the air in absolute terms.
- đ«ïž A higher dew point means more moisture in the air, which can make the environment feel stickier and more uncomfortable.
- âïž On a day with 30°C and 50% relative humidity, the dew point would be 18°C, indicating a certain level of mugginess.
- đ On a hotter day, like 35°C with the same 50% relative humidity, the dew point would rise to 23°C, making it feel much muggier.
- đ€ïž Meteorologists suggest that a dew point above 18°C starts to feel sticky and uncomfortable, influencing where you might want to spend your day.
Q & A
Why might the temperature not be the best measure of how it feels outside?
-Temperature might not be the best measure because it doesn't account for humidity, which significantly affects how hot or cold it feels to the human body.
How does the human body regulate its internal temperature?
-The human body maintains a steady internal temperature of 37 degrees Celsius for optimal enzyme function, which is crucial for life-sustaining processes.
What happens to our body when we need to cool down?
-When the body needs to cool down, blood vessels dilate to increase blood flow to the limbs for heat loss, and sweat glands produce moisture that evaporates, carrying heat away from the body.
Why does sweat not cool us down effectively in humid conditions?
-In humid conditions, the air already contains more moisture, so sweat doesn't evaporate as quickly, which means less heat is carried away, leading to a feeling of being hotter and damp.
What is relative humidity and why isn't it always helpful for determining how hot it feels?
-Relative humidity is a measure of how close the air is to being saturated with water vapor. However, it's not always helpful because the saturation point increases with temperature, meaning the same relative humidity can feel different on hotter days.
How does the saturation point of air change with temperature?
-The saturation point of air increases with temperature because warmer air can hold more water vapor. As a result, a higher temperature at the same relative humidity means there's more moisture in the air.
What is the dew point and why is it more useful than relative humidity for understanding how it feels outside?
-The dew point is the temperature at which air reaches 100% humidity and moisture condenses into dew or fog. It's more useful because it gives an absolute measure of moisture in the air, indicating how muggy it feels.
How does the dew point indicate the actual amount of moisture in the air?
-The dew point indicates the actual amount of moisture in the air by showing the temperature at which the air would be saturated with water vapor, regardless of the current temperature.
According to meteorologists, at what dew point does the weather start to feel sticky and uncomfortable?
-Meteorologists suggest that if the dew point is above 18 degrees Celsius, it's going to start to feel sticky and uncomfortable.
What is a practical suggestion for dealing with high dew points?
-When a high dew point is forecasted, it's suggested to spend the day in places with good air conditioning, such as going to see a movie or hanging out in a bookstore.
Outlines
đĄïž Understanding Temperature and Humidity
This paragraph discusses the importance of considering humidity when interpreting weather forecasts. It explains that while temperature is a common metric, it doesn't always reflect how hot or cold it feels outside due to humidity's impact. The human body maintains an internal temperature of 37 degrees Celsius, and it cools down by increasing blood flow to the limbs and producing sweat, which evaporates to remove heat. However, in humid conditions, sweat doesn't evaporate as quickly, causing a person to feel hotter and more uncomfortable. The paragraph also clarifies that relative humidity, which indicates how close the air is to being saturated with water vapor, isn't the best indicator of how hot it feels. Instead, the dew point, which is the temperature at which the air would reach 100% humidity and water vapor would condense, is a more accurate measure of how muggy the air feels. A higher dew point correlates with a stickier and more uncomfortable feeling, and meteorologists suggest that a dew point above 18 degrees is when conditions start to feel noticeably uncomfortable.
Mindmap
Keywords
đĄWeather Forecast
đĄTemperature
đĄHumidity
đĄRelative Humidity
đĄSaturation Point
đĄDew Point
đĄEvaporation
đĄBlood Vessels
đĄSweat Glands
đĄThermometer
đĄMeteorologists
Highlights
Temperature is not the best measure of how it feels outside.
Humidity is an important factor affecting how hot it feels.
The body maintains an internal temperature of 37 degrees Celsius for enzyme function.
Blood vessels dilate and sweat glands produce moisture to cool the body.
Sweat evaporation is hindered in humid conditions, trapping heat.
Relative humidity measures how close air is to saturation but isn't very helpful for feeling temperature.
Saturation point increases with temperature, affecting relative humidity readings.
Dew point is a more useful measure of how hot it feels, indicating absolute moisture in the air.
A higher dew point correlates with a more uncomfortable, muggy feeling.
Dew point above 18 degrees often signals a sticky and uncomfortable day.
Meteorologists suggest seeking air conditioning when the dew point is high.
The dew point can be used to predict the comfort level outside.
Relative humidity can be misleading due to its dependency on temperature.
The saturation point's increase with temperature affects the perception of humidity.
Dew point provides a clearer picture of the actual moisture content in the air.
A dew point of 18 degrees or higher can make the environment feel muggy and uncomfortable.
The importance of understanding dew point for personal comfort and planning outdoor activities.
Transcripts
Whether youâre planning your next vacation, or you just want to know how many layers youâll
need to put on in the morning, you probably check the weather forecast pretty often.
But you should know, before you go out with that extra jacket, that the temperature might
not be the best measure of what it actually feels like outside.
Humidity is important, too, which is why you might sometimes think the forecasters must
have been wrong, because itâs definitely about ten degrees hotter right now and youâre
covered in sweaty grossness.
Your bodyâs built-in thermostat likes to keep your internal temperature at a steady
37 degrees Celsius so that all of your enzymes can do what theyâre supposed to do... you
know ⊠keeping you alive.
That's the temperature they like.
When you need to cool off, your blood vessels open up, letting blood flow to your arms and
legs so heat can escape through your skin.
Your sweat glands also start to produce moisture, which takes a bunch of heat with it when it
evaporates.
And itâs this sweat evaporation that runs into a bit of a problem when itâs humid
out.
When thereâs more moisture already in the air, your sweat doesnât evaporate as quickly.
You end up holding onto the extra heat, so you just get hotter ⊠and damp.
Awesome.
Youâll usually see whatâs known as relative humidity in the forecast, which tells you
how close the air is to saturation, where thereâs as much water vapor in the air as
possible.
But it turns out that the relative humidity forecast also isnât super helpful for figuring
out how hot itâll feel, because the saturation point increases with the temperature.
The hotter it gets, the more energy water molecules have, which means more of them can
zoom around in the gas phase.
So you might have two days where the relative humidity is 50%.
But if itâs 30 degrees Celsius the first day and 35 degrees the second day, thereâs
way more moisture in the air on the second day, because itâs 50% of a much higher saturation
point.
Which means that the humidity on the second day is going to feel way worse.
So even though people talk about it a lot, the relative humidity forecast isnât a great
way to tell how hot it feels.
The dew point is a lot more useful.
Thatâs the temperature where, given the amount of moisture in the air, it would reach
100% humidity and the moisture would condense into dew or fog.
Whatâs helpful about the dew point is that it tells you how much moisture is in the air
in absolute terms.
So the higher the dew point, the grosser youâll feel, because thereâs more moisture in the
air.
On that first day, for example, where it was 30 degrees out with 50% relative humidity,
the dew point would be 18 degrees.
On the second day, though, the dew point would be 23 degrees, which tells you that it would
feel a lot muggier, even though the relative humidity would still be 50%.
According to meteorologists, a good rule of thumb is that if the dew point is above 18
degrees, itâs going to start to feel sticky and gross.
So if you see a higher dew point in the forecast, you might want to spend the day somewhere
thereâs lots of good air conditioing.
Go see a movie, or hang out at Barnes and Noble, reading books.
Thanks to patreon patron Miranda McCarthy for asking this question, I've actually been
curious about it, so thank you.
And thanks to all our patrons, who keep these answers coming.
If youâd like to submit a question to be answered, you can go to patreon.com/scishow.
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