This work by Ng Wai Fong of the Department of Applied Physics, The Hong Kong Polytechnic University, is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Hong Kong License, based on the information provided by Creative Common. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-sa/3.0/hk/deed.zh_HK.

Weather and Our Feelings

(Author: Ng Wai Fong)

The Hong Kong Polytechnic UniversityDepartment of Applied Physics

This work by Ng Wai Fong of the Department of Applied Physics, The Hong Kong Polytechnic University, is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Hong Kong License, based on the information provided by Creative Common. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-sa/3.0/hk/deed.zh_HK.

Temperature and thermal feelings

• What does the temperature in weather report refer to?– Temperature of Air

• What is cold/hot?– The feelings of human on temperature

• 15 ℃ = Cold? 35 ℃ = Hot?

This work by Ng Wai Fong of the Department of Applied Physics, The Hong Kong Polytechnic University, is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Hong Kong License, based on the information provided by Creative Common. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-sa/3.0/hk/deed.zh_HK.

Related Weather Warnings from Hong Kong Observatory

Cold Weather Warning– Winter Only

Very Hot Weather Warning – Summer Only

Is it enough?

This work by Ng Wai Fong of the Department of Applied Physics, The Hong Kong Polytechnic University, is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Hong Kong License, based on the information provided by Creative Common. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-sa/3.0/hk/deed.zh_HK.

Weather and Our Feelings

• Factors that influence us on the thermal feelings:– Temperature– Wind Speed– Relative humidity– Radiation of the Sun

• Example: – A hot weather with high relative humidity hinder heat loss

by the evaporation of sweat, low wind speed will also lower heat loss from human body, thus increasing the level of discomfort.

This work by Ng Wai Fong of the Department of Applied Physics, The Hong Kong Polytechnic University, is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Hong Kong License, based on the information provided by Creative Common. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-sa/3.0/hk/deed.zh_HK.

Heatstroke

• Under very hot weather, who are having a greater risk of a heatstroke?

Standard Chartered Hong Kong

Marathon 2010.

The heat and humidity sent 55 racers

to hospital to be treated for heat stroke

or dehydration

Buses without air conditioning pose serious health risks. Bus drivers felt sick and got heatstroke.

This work by Ng Wai Fong of the Department of Applied Physics, The Hong Kong Polytechnic University, is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Hong Kong License, based on the information provided by Creative Common. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-sa/3.0/hk/deed.zh_HK.

Weather and Our FeelingsScientists make use of weather data to estimate human feelings•Thermal comfort (熱舒適度 )

– The satisfactory level of human towards the coldness/hotness of environment

• Eg. Hot, warm, slight warm, neither cold nor hot, just right, slight cool, cool, cold

• The condition of the heat exchange between human body and environment

– Factors• Temperature• Humidity• Air Current• Hot Radiation• Metabolism• Clothing

This work by Ng Wai Fong of the Department of Applied Physics, The Hong Kong Polytechnic University, is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Hong Kong License, based on the information provided by Creative Common. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-sa/3.0/hk/deed.zh_HK.

Weather and Our Feelings

Ways to express the comfort level due to heat:• Net Effective Temperature (NET) • Heat Index (HI) – Summer Only• Humidex (HMI) – Summer Only• Apparent Temperature (AT) • Wind Chill Index (WCI) – Winter• Wet Bulb Globe Temperature Index (WBGT)2008 Summer Olympics Equestrian Events in Hong Kong

This work by Ng Wai Fong of the Department of Applied Physics, The Hong Kong Polytechnic University, is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Hong Kong License, based on the information provided by Creative Common. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-sa/3.0/hk/deed.zh_HK.

(Activity 1) Calculations:Apparent Temperature AT

• AT = Ta + 0.33×e − 0.70×ws − 4.00 where, e = rh / 100 × 6.105 × exp ( 17.27 × Ta / ( 237.7 + Ta ) )

Air Temperature, Ta (°C)

25 30 35 38

Relative Humidity,rh (%) 50 50 50 50

Wind Speed, ws (km/h) 5 5 5 5

Apparent Temperature, AT (°C)

22.71 29.48 36.74 41.39

This work by Ng Wai Fong of the Department of Applied Physics, The Hong Kong Polytechnic University, is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Hong Kong License, based on the information provided by Creative Common. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-sa/3.0/hk/deed.zh_HK.

(Activity 1) Calculations:Apparent Temperature AT

• AT = Ta + 0.33×e − 0.70×ws − 4.00 where, e = rh / 100 × 6.105 × exp ( 17.27 × Ta / ( 237.7 + Ta ) )

Air Temperature, Ta (°C)

30 30 30 30

Relative Humidity, rh (%) 20 40 60 80

Wind Speed, ws (km/h) 5 5 5 5

Apparent Temperature, AT (°C)

25.29 28.08 30.87 33.66

This work by Ng Wai Fong of the Department of Applied Physics, The Hong Kong Polytechnic University, is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Hong Kong License, based on the information provided by Creative Common. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-sa/3.0/hk/deed.zh_HK.

(Activity 1) Calculations:Apparent Temperature AT

• AT = Ta + 0.33×e − 0.70×ws − 4.00 where, e = rh / 100 × 6.105 × exp ( 17.27 × Ta / ( 237.7 + Ta ) )

Air Temperature, Ta (°C)

35 35 35 35

Relative Humidity, rh (%) 50 50 50 50

Wind Speed, ws (km/h) 0 5 10 20

Apparent Temperature, AT (°C)

40.24 36.74

33.24 26.24

This work by Ng Wai Fong of the Department of Applied Physics, The Hong Kong Polytechnic University, is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Hong Kong License, based on the information provided by Creative Common. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-sa/3.0/hk/deed.zh_HK.

(Activity 2) Scientific Experiment:Estimating Human’s Feelings on

Weather• Refer to the worksheet

(Scientific Experiment: Estimating Human’s Feelings on Weather by Ng Wai Fong)

This work by Ng Wai Fong of the Department of Applied Physics, The Hong Kong Polytechnic University, is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Hong Kong License, based on the information provided by Creative Common. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-sa/3.0/hk/deed.zh_HK.

(Activity 3) Investigation on the Wet Bulb Globe Temperature

Video:http://www.weather.gov.hk/wservice/cstdi/cstdic.htm

Discussions:•What is the use of Wet Bulb Globe Temperature (WBGT)?•Why Heat Stress Index is better than other weather information?•Should Heat Stress Index be used and disseminated?•Students can discuss the issues about disseminating Heat Stress Index to the public through a role play with different characters:

– Representative of the industrial and commercial sector– Representative of the transport services– Director of the Hong Kong Observatory– School Principal