Comfort

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The surface wind influences personal comfort in cold climates in terms of the windchill (Note 3.E). Even indoors, a cold draught of only 0.3 m/s can be uncomfortable, though up to 0.6 m/ s is reckoned reasonable ventilation in moderate climates. Higher velocities lead to papers being blown about. The achievement of comfortable ventilation indoors depends on appropriate building design, which is considered in Note 14.B and Chapter 16.

A pleasant breeze outdoors has a speed of about 2 m/s, but over 6 m/s can be annoying, disturbing the hair and making your clothes flap, with dust and litter blown about if the wind is gusty. The force of a strong wind can be considerable (Note 14.B). The elderly may find it hard to walk against a wind above 7 m/s, and an opposing wind of 9 m/s is equivalent to walking up a hill with a slope of 1 in 20. It is necessary to lean at 20 degrees into Antarctic winds of 24 m/s, and a gust of that speed will knock people over.

Table 14. 1 The Beaufort scale of wind speeds

Beaufort

Scale Description

At sea

On land

Knots

M/s

Smoke vertical

0

0

Smoke drifts

2

1.0

Leaves rustle

6

3.1

Wind felt on face

9

4.6

Small leafy trees sway

17

8.7

Large branches sway

23

12

Whole trees move

29

15

Twigs break off, walking

impeded

37

19

Removes tiles

43

22

Trees blown down

50

26

Much damage

58

30

Extreme damage

64

33

11 12

Calm Light air Light breeze Gentle breeze Fresh breeze Strong breeze Moderate gale Gale

Strong gale Storm

Hurricane *

Flat sea Ripples Wavelets Breaking wavelets Moderate waves Spray, white foam Heaped sea

Long crests and blown foam

10 m waves and reduced visibility

Heavy rolling seas, overhanging crests Spray obscures Sea white with foam

: The threshold peak wind speed in a tropical cyclone (Table 13.2)

half feather = 5 knots direction of air flow/ \

whole feather = 10 knots flag = 50 knots \y o—' 7 d4"

half feather = 5 knots of a column of 1 km by 5 K, for instance,

calm

Figure 14.4 Symbolic representation of the wind and its direction at any moment, at the place indicated by the location of the circle at the end of the arrow.

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Renewable Energy 101

Renewable Energy 101

Renewable energy is energy that is generated from sunlight, rain, tides, geothermal heat and wind. These sources are naturally and constantly replenished, which is why they are deemed as renewable. The usage of renewable energy sources is very important when considering the sustainability of the existing energy usage of the world. While there is currently an abundance of non-renewable energy sources, such as nuclear fuels, these energy sources are depleting. In addition to being a non-renewable supply, the non-renewable energy sources release emissions into the air, which has an adverse effect on the environment.

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