Daily Variation

Surface air generally contains more moisture in summer (Table 6.2, Table 6.3, Figure 6.7 and

Several factors alter the water content of the surface atmosphere during the day. Weather

Table 6.3 Effects of latitude, season and height above sea-level on monthly mean mixing ratios

Mixing ratio (g/kg)

Table 6.3 Effects of latitude, season and height above sea-level on monthly mean mixing ratios

Place

Lot. (°SJ

Month

Sea level

1,500 m

3,000 m

5,500 m

Lima

12

Jan

13.7

9.8

5.0

2.6

July

10.0

3.2

2.5

1.6

Nandi

18

Jan

18.2

11.9

6.1

2.4

July

13.4

8.3

3.9

1.5

Pretoria*

26

Jan

-

12.6

7.3

1.9

July

-

4.7

1.6

0.3

Invercargill

46

Jan

7.5

4.6

2.5

0.9

July

4.6

2.7

1.2

0.4

Argentine Island

65

Jan

3.3

2.3

1.4

0.4

July

1.4

1.3

0.7

0.2

Halley Bay

76

Jan

2.0

1.4

0.7

0.3

July

0.8

0.5

0.3

-

South Polef

90

Jan

-

-

0.2

-

* Pretoria is at 1,368 m above sea-level t The South Pole is at 2,992 m above sea-level

* Pretoria is at 1,368 m above sea-level t The South Pole is at 2,992 m above sea-level

Table 6.4 Monthly variations of the daily mean temperature and 9 a.m. values of the dewpoint, vapour pressure, saturation deficit and relative humidity, at Sydney airport in 1969

(°C)

Vapour pressure (hPa)

Saturation deficit (hPa)

Relative humidity (%)

Mixing ratio (g/kg)

January

23.7

17.2

19.6

9.7

67

12.0

February

22.3

17.2

19.6

7.3

73

12.0

March

21.7

17.2

19.6

6.4

75

12.0

April

18.7

11.7

13.7

7.9

63

8.4

May

14.9

9.4

11.8

5.1

70

7.2

June

12.7

7.8

10.6

4.1

72

6.5

July

12.2

6.7

9.8

4.4

69

6.0

August

13.2

8.9

11.4

3.8

75

6.9

September

13.6

6.1

9.4

6.2

60

5.8

October

16.9

11.7

13.7

5.5

71

8.3

November

19.7

13.3

15.3

6.3

71

9.4

December

21.2

12.8

14.8

10.4

59

9.1

changes alter the import of moisture in winds, and there are nocturnal dew formation (which subtracts moisture from the surface air), evaporation of the dew in the morning (which raises the air's humidity again), daytime convection (which stirs dry air from aloft into the surface air), and sea breezes (which bring marine air inland in the afternoon). The outcome is that the dewpoint decreases in summer between 9 a.m. and 3 p.m. anywhere in Australia, but in winter there tends to be an increase in coastal south-east Australia.

Was this article helpful?

0 0
Solar Power

Solar Power

Start Saving On Your Electricity Bills Using The Power of the Sun And Other Natural Resources!

Get My Free Ebook


Post a comment