Science

1. CLASS: Integrated Science Form 5
TOPIC OF LESSON: Humidity & Cooling
SECTION: B - The Home and Workplace

2. OBJECTIVES
SYLLABUS OBJECTIVE(S) [OBJETIVO DE SYLLABUS]
Candidate should be able to:
Explain the cooling effects of evaporation;
El candidato debe ser capaz de:
Explica los efectos refrescantes de la evaporación;

3. OBJECTIVES
LESSON OBJECTIVE(S) [OBJETIVOS DE LA LECCIÓN]
By the end of this lesson, the student should be able to:
● Describe humidity and its unit of measurement
● Describe the effect of humidity on human beings and the building environment
Al final de esta lección, el estudiante debe ser capaz de:
● Describir la humedad y su unidad de medida.
● Describir el efecto de la humedad en los seres humanos y en el edificio.

4. GLOSSARY [Will fit better in platform]
ENGLISH SPANISH
airflow flujo de aire
chapped lips labios agrietados
dew point punto de rocío
exterior exterior
health problems problemas de salud
humidity humedad
hygrometer higrómetro
inadequate inadecuado
leak fuga
maximum máximo
mould infestation infestación de moho
relative humidity humedad relativa
saturated saturado
sweat sudor
sweaty sudoroso

5. INTRODUCTION
Click triangle and watch
the video.
Why doesn’t he get
sweaty? Is it because
the place is cold?

6. INTRODUCTION cont’d/…
In the video, Nas and his friends did not get sweaty because the air is very dry and hot.
We already learned that sweat is used to keep us cool. So when we get hot, we sweat and its
evaporation takes the heat with it.
But…
Evaporation needs more than heat from the surroundings. It also needs favourable humidity.
In this lesson, we will look at humidity.
What is humidity?
How is it measured?
How does it affect evaporation?
How does it affect us?

7. WHAT IS HUMIDITY?
Watch the video below and answer the following questions in your notebook…
1. What is humidity?
2. What is water vapour?
3. If the air is dry, what would be the percentage humidity?
4. What percentage humidity would produce rain?

8. EXPLANATION cont’d/…
Click the triangle
and watch the
video.
Answer the
questions given in
the previous slide in
your notebook.

9. A Unit of Measurement for
Humidity is
‘Percentage Relative Humidity’
(%RH).

10. How Does Humidity Affect Us?
HIGH HUMIDITY (95 %RH)
When humidity is high, there is a lot of water vapour in the
air, close to the maximum it can hold.
This situation is opposite to the Introduction video. The air is
already full of water vapour. The sweat evaporates from the
body very slowly. People feel hot & sticky, and they cannot
cool down.
People can become very uncomfortable & cannot work very
well.

11. How Does Humidity Affect Us?
LOW HUMIDITY (65 %RH & Below)
When humidity is low, there is a not a lot of water
vapour in the air. The air is dry.
People would not get sweaty, because it would
evaporate very quickly.
Even if it is hot, people would feel comfortable.
However, people could suffer from dry skin and
chapped lips.

12. Other Effects of High Humidity
“Although this home
experienced minor exterior
damage from Hurricane
Katrina, small leaks and
inadequate airflow permitted
mold infestation.”
Wikipedia

13. High humidity encourages
growth of bacteria and fungi
(mould).
This can cause health
problems and unpleasant
odours.

14. SUMMARY
● Humidity is a measure of how much water vapour is in the air.
● The hotter the air, the more water vapour it can hold before it gets saturated.
● A unit of measurement for humidity is ‘percentage relative humidity’ (%RH).
● Humidity of the environment affects how quickly sweat evaporates.
● Low humidity leads to rapid evaporation of sweat. People don’t get sweaty and are
relatively comfortable, even if temperatures are high.
● High humidity slows down the evaporation of sweat. People get sweaty and sticky. They
get uncomfortable as a result and don’t work as well.
● High humidity encourages growth of bacteria and fungi in buildings. This can lead to
health issues and unpleasant odours.

15. Now Let’s See if You Understand...
Go to this link. It is a quiz.
https://quizizz.com/join?gc=586618&source=liveDashboard

16. REFERENCES
Derek McMonagle, 2012, Model Answers - Integrated Science (Worked Solutions fo CSEC Examinations 2006 - 2010),
Macmillan Education, Oxford, viewed on 8th July 2019
Donna Bynoe-Arthur, 2004, Integrated Science - A Concise Revision Course for CXC, Nelson Thornes Ltd.,
Cheltenham, viewed on 8th July 2019
Infrogmation (Wikipedia), 28 October 2005, Post-Katrina Mold in House on Dublin Street Carrolton New Orleans.jpg,
viewed on 8th July 2019, <https://en.wikipedia.org/wiki/Indoor_mold#/media/File:Post-
Katrina_Mold_in_House_on_Dublin_Street_Carrollton_New_Orleans.jpg>
Mindset Well, 28th June 2018, Nas Daily - Where You Don’t SWEAT !!, viewed on 8th July 2019,
<https://youtu.be/Zmqt7sZZyq0>
NA, Hot Weather Cliparts #2466152, viewed on 8th July 2019, <http://clipart-library.com/clipart/1622333.htm>