PHY_10_12_V2_TG_Air humidity,dew point

Theoretical material for the lesson, definitions for concepts 

If you have allergies or asthma, you probably know that the humidity level inside your home matters. Excessive levels of humidity can cause mold growth, trap dirt and other allergens in the air and cause a number of health problems. Consistent exposure to low humidity can also cause health issues, especially throat, nose and eye irritation. In addition to health problems, too high or low levels of humidity may cause structural damage to your home. Controlling humidity is fairly easy to do and can help prevent poor air quality, exacerbated allergies and asthma and home damage. Generally, humidity most often refers to relative humidity, not absolute humidity.

Below, learn more about what relative humidity is, where it comes from, side effects of too low or too high humidity and how to maintain ideal levels of humidity in your home.

What is relative humidity?

Relative humidity is the amount of moisture in the air at a certain temperature compared to what the air can “hold” at that temperature. To be clear, air is not actually capable of physically holding onto water vapor because it moves too quickly. When the air in your home reaches a specific capacity of water vapor, it will condense as moisture, causing the air to feel damp. When relative humidity gets too high, usually above 50%, mold and mildew growth and trapped allergens become more likely which, in turn, may cause allergy and asthma symptoms to appear.

When you’re trying to figure out how to make the air in your home healthy, relative humidity is an important factor to consider. It allows you to assess the amount of moisture present, so you can understand how much humidity you have and decide which type of dehumidifier or humidifier is best for you. How much relative humidity is present in your home will depend on the region and climate you live in.

Mathematically, relative humidity is the gram-per-cubic-meter (g/m³) measure of the water vapor in the air divided by the gram-per-cubic-meter (g/m³) measure of the maximum amount of moisture the air can hold at a given temperature. The resulting number is multiplied by 100 to get a percentage, which is the relative humidity. Hygrometers and dehumidifiers can help you calculate the current relative humidity in your home.

What is the difference between absolute humidity and relative humidity?

Absolute humidity is the actual amount of moisture in the air. The National Weather Service describes it specifically as a measure of the amount (g/m³) of water vapor in the air or atmosphere, regardless of the temperature. The more water vapor in the air, the higher the absolute humidity. What we “feel” as humidity in the air is the absolute humidity.

Relative humidity is measured as a percentage or ratio of the amount of water vapor in a volume of air RELATIVE to a given temperature and the amount it can hold at that given temperature. Warm air can hold more moisture than cold air. This means that at the same absolute humidity, the relative humidity can be lower in warm air and higher in cold air.

Though they may seem similar, the terms absolute humidity and relative humidity cannot be used interchangeably.

What makes air healthy?

Most people spend a majority of their time indoors. You may be surprised to find out that levels of indoor air pollutants may be 2 to 5 times higher than the levels of outdoor air pollutants. While you may be able to see dust on a bookshelf or dirt on the floor and know that it is time to clean, you cannot always see what is polluting your air.

When any of these pollutants are present, it is safe to say your air needs to be cleaned. Conversely, healthy air is:

·         Made up of less than 50% relative humidity

·         Free of toxins

·         Well-ventilated and fresh

What is an ideal level of relative humidity for a home?

Humidity above 50% is typically considered too high, while humidity below 30% is usually too low. That means that the ideal range of relative humidity for a home is between 30% and 50%, according to the EPA. This, of course, depends on the climate you live in, as well as your personal preference.

How to keep the relative humidity in your home at an optimal level

Though there are many ways in which humidity levels can become too high or too low, as well as many health and home problems caused by an imbalance of humidity, there are also simple ways to keep it at an ideal level. To keep the relative humidity in your home between the ideal levels of 30% and 50%, you may want to consider using either a dehumidifier or a humidifier.

Instructions for demonstrations and safety 

Bags tucked neatly under tables to avoid anybody accidentally tripping up.

Shoulder Blade Pinch

Sit up straight with both feet on the floor and hands by your sides. Keeping your neck straight, draw your shoulder blades together. Don’t raise your shoulders up. Try to squeeze your shoulder blades together. Then, draw your shoulders forward and bring them together as close as you can. Repeat this exercise several times at a moderate pace.

Additional guidelines for organizing a lesson 

Task: continue the sentences.

Aim: check knowledge of students about topic

Define the topic of the lesson and lesson’s objectives.

Motivation for learning activities

Task: watch the video and study new topic

Teacher’s action: show the video, stop it during translation and ask students questions about new material, organize the students’ work of making notes, ask some questions, and check student’s work.

Additional multilevel (on differentiation) tasks

The following 3 questions can be assigned to weak students: 1, 2, 8.

The following 6 questions can be assigned to the average students: 1,2,3, 5,8,9,10.

The following 10 questions can be assigned to the strong students: 1-10

1. The amount of water in the air is called ____.

2. 

When there is a lot of humidity, the air feels _____.

A. Dry

B. Wet

C. Wet and dry

D. Fresh

3. 

What happens to water vapor when it rises into the air and cools down?

A. It will condense in the ground as dew

B. It will make a hot day feel even hotter

C. It will condense into liquid water

D. It will evaporate into teeny-tiny drops

4. 

Warm air can hold more water than cool air.

A. True

B. False

5. 

What is it called when water condenses on the ground?

Discuss

6. 

Humidity can make a hot day feel cooler.

A.           True

B.        False

7. 

If you get too hot, you should:

A.        Slow down

B.        Drink some water

C.        Cool off

D.        All of the above

8. Point at which gases turn in to liquid is called its

A.    peak point

B.     dew point

C.     converting point

D.    equilibrium point

Answer 

9. Amount of water vapor in air is regarded as

A.    water vapor

B.     humidity

C.     mildness

D.    pressure

10. Factor influencing humidity includes

E.       water

F.        temperature

G.      pressure

H.      osmosis

List of useful links and literature 

https://www.youtube.com/watch?v=QbcaCxuA1LI

https://www.youtube.com/watch?v=PNsF5PzNVJo

http://www2.ca.uky.edu/agcomm/pubs/aen/aen87/aen87.pdf

https://www.tqcsheen.com/en/product/sling-psychrometer-en/

http://allinair.ca/the-difference-between-a-psychrometer-and-a-hygrometer/

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