5. Decide whether the following statements are true or false according to the text.

1) Air is a mixture of gases, mainly hydrogen and oxygen.

2) Air has weight and a volume.

3) If gravity didn't exist, then air pressure would exist.

4) There is no difference between mass and weight.

5) Temperature and pressure are interrelated.

6) Air expands when it gets cold and contracts when it gets hot.

7) The amount of air contained within a box will vary with temperature and pressure.

8) Air at Standard conditions is denser than air at Normal conditions.

9) By compressing the sponge we can reduce its ability to hold water.

10) If we cool down hot air, the water vapour condenses out into liquid.

6. Answer the following questions.

1) What is the definition of air?

2) What hard matter does air contain?

3) What do the variables depend upon?

4) How can air weight be demonstrated?

5) What is air pressure caused by?

6) Does air have temperature? Prove it.

7) What is the Standard Temperature and Pressure condition?

8) How is Normal Volume measured?

9) Does air contain water vapour? Prove it.

10) Hot air holds more water than cold air, doesn’t it?

7. Find key words and phrases which best express the general meaning of each part.

8. Write a summary of Text 1.

LANGUAGE FOCUS

9. Choose the contextual meanings of the words written in bold in Text 1.

1) accurate

a) правильный	c) определенный
b) меткий	d) точный

2) gravity

a) вес	c) плотность
b) тяжесть	d) сила притяжения

3) statement

a) утверждение	c) установка
b) предложение	d) заявление

4) to contract

a) стягивать	c) сжимать
b) давать усадку	d) сокращать

5) hard

a) тяжело	c) крепко
b) трудно	d) настойчиво

6) to qualify

a) уточнять	c) ограничивать
b) контролировать	d) квалифицировать

10. Form the nouns from the following verbs.

to pump →…	to condensate →…
to compress →…	to qualify →…
to saturate →…	to consider →…
to contract →…	to reduce →…
to collapse →…	to perform →…
to interrelate →…	to expand →…

11. Fill in the correct prepositions, translate the phrases, then choose any three items and make up sentences of your own.

1) to get rid … misunderstandings; 2) to depend … sth; 3) to demonstrate sth … weighing; 4) to weigh sth… a set … scales; 5) to be full … compressed air; 6) to be … pressure; 7) to be caused …gravity; 8) to be interrelated … sth; 9)to pump … sth; 10) to be measured … standard conditions; 11) to have a humidity … 100%; 12) to condense out … liquid.

12. Translate the following words and phrases into English using the vocabulary of the text.

Водный пар, климатические условия, состав воздуха, точные весы, сжатый воздух, понижение давления, удельный объем, зависеть от температуры, относительная влажность, поглощать, конденсировать в жидкость.

13. Translate the italicized passage in written form paying attention to the Conditionals.

IT’S IMPORTANT TO KNOW

14. Read the following text and fill in the words from the list below.

a) content	d) velocity	g) devices
b) pressure	e) measured	h) dry
c) desiccant	f) humidity	i) temperature

Meteorological offices and aviation textbooks use the following figures:

The weight of 1) _____ air (no moisture content) at 0 deg C and under a normal atmospheric 2) _____ of 1013 mbar is 1.293 Kg/cu metre.

The weight of dry air (no moisture content) at 0 deg C and at a pressure of 1000 mbar (1 Bara) is 1.275 Kg/cu metre.

The amount of water vapour contained in air can be 3) _____ in one of several ways:

The Dewpoint Method

Air is cooled down and the 4) _____ at which condensation begins is measured. The actual water 5) _____ of the air is then obtained from a set of steam tables.

Hygrometers

These air direct reading 6) _____ which usually measure the change in dimensions of a material due to the amount of moisture it contains. Older hygrometers used wood or paper and the changes in dimensions due to 7) _____ would take ages to stabilise. Modern probes use metal oxides such as aluminium and these hygrometers only take a few minutes to get within 5% of the final reading. However, depending upon the size of the system it may take another day to finally stabilise.

Psychrometry

These measure the wet bulb and dry bulb temperature across thermometers, thermocouples or resistance thermometers. Still air humidity is measured using Sling Psychrometers or Aspiration Psychrometers. In any event, a correction to the wet bulb temperature is required if the air 8) _____ past the wet bulb is not between 800-900 ft per min.

Chemical Analysis

This is obtained by exposing a known chemically dry 9) _____ to the air and then measuring the increase in moisture content over a fixed time interval

GRAMMARFOCUS.