may i know which one is cooler at 3pm?

place #1

31 deg C

Precipitation: 50%

Humidity: 70%

Wind: 13km/h

place #2

34 deg C

Precipitation: 40%

Humidity: 47%

Wind: 11km/h

The one which has a temperature 3 degrees less than the other?

There is humidity in the air it makes the weather feel more extreme
then it may actually be for example if it is 40 Degrees and there is
40% humidity it may feel like its about 35 degrees but with 70% humidity it may
feel like its 45 degrees that is because the air is denser due to the presence of moisture

So my guess the one with the Higher temperature but lower humidity is cooler, but I could be wrong

Edited June 3, 201313 yr by MJCM

I seem to remember something about this from some college courses in HVAC (heating, ventilating, airconditioning) Design.

There's a nice wikipedia article on the entire subject, with a nifty table that I remember from an ASHRAE handbook.

http://en.wikipedia.org/wiki/File:Temperature-relative_humidity_chart_-_PMV_method.pdf

It considers two of the four variables listed by the OP: temperature and humidity. Precipitation doesn't enter into the considerating -- either it's raining or it isn't. It can't be 40% raining. Air speed does enter into the perception of comfort, but I think it would be a third varable that would be shown graphically with a 3-D model.

As you can see, neither place is within the comfort zone of 90% of the human population. But, you can plot the two points and see that the conditions for Place 2 are further away from the comfort zone than Place 1. The fact that the wind velocity is higher in Place 1 only increases the comfort of the place.

Edited June 3, 201313 yr by NancyL

place 1 is cooler, place 2 is more bearable

Not Chiang Mai Specific - Moving to General

Let's ask Jay-Z

I seem to remember something about this from some college courses in HVAC (heating, ventilating, airconditioning) Design.

There's a nice wikipedia article on the entire subject, with a nifty table that I remember from an ASHRAE handbook.

http://en.wikipedia.org/wiki/File:Temperature-relative_humidity_chart_-_PMV_method.pdf

It considers two of the four variables listed by the OP: temperature and humidity. Precipitation doesn't enter into the considerating -- either it's raining or it isn't. It can't be 40% raining. Air speed does enter into the perception of comfort, but I think it would be a third varable that would be shown graphically with a 3-D model.

As you can see, neither place is within the comfort zone of 90% of the human population. But, you can plot the two points and see that the conditions for Place 2 are further away from the comfort zone than Place 1. The fact that the wind velocity is higher in Place 1 only increases the comfort of the place.

I agree with Nancy humidity does not change the temperature place 1 is still cooler than place 2.For most people it just feels hotter.

place 1 is cooler in number.

place 2 is 'perceived' cooler by less humidity ( water content in air ). some weather media say 'feel like XX degree'.

I seem to remember something about this from some college courses in HVAC (heating, ventilating, airconditioning) Design.

There's a nice wikipedia article on the entire subject, with a nifty table that I remember from an ASHRAE handbook.

http://en.wikipedia.org/wiki/File:Temperature-relative_humidity_chart_-_PMV_method.pdf

It considers two of the four variables listed by the OP: temperature and humidity. Precipitation doesn't enter into the considerating -- either it's raining or it isn't. It can't be 40% raining. Air speed does enter into the perception of comfort, but I think it would be a third varable that would be shown graphically with a 3-D model.

As you can see, neither place is within the comfort zone of 90% of the human population. But, you can plot the two points and see that the conditions for Place 2 are further away from the comfort zone than Place 1. The fact that the wind velocity is higher in Place 1 only increases the comfort of the place.

I agree with Nancy humidity does not change the temperature place 1 is still cooler than place 2.For most people it just feels hotter.

Not true. Yes, humidity doesn't change the temperature, but it can change the perception of comfort. Take a look at that chart and you'll see it is possible for a higher temperature to feel more comfortable than a lower one if there it is a big difference in humidity. It just that in the two cases presented by the OP, there isn't enough difference in the humidity to overcome the difference in the temperature.

I was always amused by the weather forecasters on Houston television making a meal out of 'heat index' when saying, "It's 89 outside right now but with the HEAT INDEX, that feels like 100." I always considered that it was invented to make the weatherman have something more to blether about. I mean 'feels like' is different things to someone who just stepped out of an air-conditioned mall and someone who has been riding around in a Metro bus with a broken air conditioner; the former wants to get back inside the mall whereas the latter can't wait to get off the bus.

Now something I DO agree with is the Wind Chill Factor. After working on the North Slop of Alaska, that scientific phenomenon is real!