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^^ Haha my family is the exact opposite, they use wind chill as if it was the actual temperature. I remember once when I lived in North GA, there was a morning with a 12 F temperature and a -4 F wind chill. My mom told me it was -4 F outside and I got super excited. My excitement was about half gone when I found out that -4 F was merely the wind chill, and that the actual temperature was 12 F.
Still bloody freezing lol. I remember a time when I was at highschool, and the temperature at lunchtime was 7.5°C, but the wind chill was -5°C because of 100km/h winds coming from the SW. My friends were basically begging a nearby teacher to let them into a classroom but I was enjoying this rare experience. I think it also hailed that day too.
Windchill must depend on wind direction (from warm/cool wind current), its like setting heat at 20c feels warmer than setting ac at 20c, cause heater blows warmer air than setting while ac blows cooler air
Because relative humidity doesn't tell the whole story. It could be 0 F with 100% relative humidity or 100 F with 40% humidity, which one is more humid? Dew Point is a true measure of how humid it really is. The hotter the air is, the more moisture it can hold. That's why simply using relative humidity is stupid.
Thanks for the info.
But as long as they report both temperature and relative humidity, doesn't that give an accurate indication of how it will feel outside?
But as long as they report both temperature and relative humidity, doesn't that give an accurate indication of how it will feel outside?
Kind of but not really.
The dew point is a direct measure of how much water vapor is in the air. It does not depend on temp or anything else, only how much moisture is in the air. You can begin to feel it at around a 60 F dewpoint and at 70 F it becomes very uncomfortable.
Relative humidity on the other hand is relative to the actual amount of water vapor in the air AND the amount of water vapor the air can hold (which is based on the temp). Your bodys ability to cool itself is directly impacted by the actual amount of water vapor in the air. Not the amount of wator vapor in the air in relation to the amount of water vapor the current air temp can hold. Relative humidity is of little help in informing us exactly how much water vapor is in the air.
So the weatherman can tell you
1. The dewpoint. In which case you know immediately that at 60 you start to feel the humidity at 65 it becomes a little uncomfortable and above 70 its gonna be really uncomfortable outside
2. The relative humidity. In which case you don't know squat because you have no idea how much moisture is in the air unless you have memorized how much water vapor the air at the current temp can hold and multiply that by the relative humidity percent.
Examples
1. Weatherman says its gonna be 80 F tomorrow and the dew point will be 70 F.....I know its gonna be a hot humid day and can expect to get soaked with sweat if I am doing outdoors activities
2. Weatherman says its gonna be 80 F tomorrow with a relative humidity of 60%.....I dunno what to expect, maybe a little humid but not real sure.
Last edited by justanokie; 06-29-2015 at 11:19 AM..
Still bloody freezing lol. I remember a time when I was at highschool, and the temperature at lunchtime was 7.5°C, but the wind chill was -5°C because of 100km/h winds coming from the SW. My friends were basically begging a nearby teacher to let them into a classroom but I was enjoying this rare experience. I think it also hailed that day too.
Lol yeah still cold as hell, but 12 F (-11 C) is kind of a standard strong cold snap in winter outside the UHI effect in North GA. -4 F would have been nearly historic and much more exciting.
Quote:
Originally Posted by Ariete
Well,
- meteorologists here aren't local, but nationwide
- meteorologists are not allowed to express opinions
- meteorologists don't mention relative humidity
- mereorologists don't mention dew points
I wish that was the case here. Meteorologists express their ridiculous opinions all the time.
Honestly watching forecasts from Spain or the UK the meteorologists over there seem a lot more well-informed and much more in-depth with their analysis than the ones here in the US. I wonder if anyone else has noticed this.
The dew point is a direct measure of how much water vapor is in the air. It does not depend on temp or anything else, only how much moisture is in the air. You can begin to feel it at around a 60 F dewpoint and at 70 F it becomes very uncomfortable.
Relative humidity on the other hand is relative to the actual amount of water vapor in the air AND the amount of water vapor the air can hold (which is based on the temp). Your bodys ability to cool itself is directly impacted by the actual amount of water vapor in the air. Not the amount of wator vapor in the air in relation to the amount of water vapor the current air temp can hold. Relative humidity is of little help in informing us exactly how much water vapor is in the air.
So the weatherman can tell you
1. The dewpoint. In which case you know immediately that at 60 you start to feel the humidity at 65 it becomes a little uncomfortable and above 70 its gonna be really uncomfortable outside
2. The relative humidity. In which case you don't know squat because you have no idea how much moisture is in the air unless you have memorized how much water vapor the air at the current temp can hold and multiply that by the relative humidity percent.
Examples
1. Weatherman says its gonna be 80 F tomorrow and the dew point will be 70 F.....I know its gonna be a hot humid day and can expect to get soaked with sweat if I am doing outdoors activities
2. Weatherman says its gonna be 80 F tomorrow with a relative humidity of 60%.....I dunno what to expect, maybe a little humid but not real sure.
Great post, I had a reply also but I couldn't have worded it any better myself.
The dew point is a direct measure of how much water vapor is in the air. It does not depend on temp or anything else, only how much moisture is in the air. You can begin to feel it at around a 60 F dewpoint and at 70 F it becomes very uncomfortable.
Relative humidity on the other hand is relative to the actual amount of water vapor in the air AND the amount of water vapor the air can hold (which is based on the temp). Your bodys ability to cool itself is directly impacted by the actual amount of water vapor in the air. Not the amount of wator vapor in the air in relation to the amount of water vapor the current air temp can hold. Relative humidity is of little help in informing us exactly how much water vapor is in the air.
So the weatherman can tell you
1. The dewpoint. In which case you know immediately that at 60 you start to feel the humidity at 65 it becomes a little uncomfortable and above 70 its gonna be really uncomfortable outside
2. The relative humidity. In which case you don't know squat because you have no idea how much moisture is in the air unless you have memorized how much water vapor the air at the current temp can hold and multiply that by the relative humidity percent.
Examples
1. Weatherman says its gonna be 80 F tomorrow and the dew point will be 70 F.....I know its gonna be a hot humid day and can expect to get soaked with sweat if I am doing outdoors activities
2. Weatherman says its gonna be 80 F tomorrow with a relative humidity of 60%.....I dunno what to expect, maybe a little humid but not real sure.
Temperature and relative humidity are all you need to calculate dewpoint. I'd say anyone who's enough of a weather nerd to get annoyed that the TV weather forecaster doesn't say the dewpoint should probably just get better at doing that calculation in their head.
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I think it also hailed that day too.
