The human response to climate
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The Human Response to Climate. Physical environment is the single most important determination of human actions and activities-environmental determinism Climate is a major component of the environment, gave rise to climate determinism. Physiological responses

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The Human Response to Climate

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The Human Response to Climate

Physical environment is the single most important determination of human actions and activities-environmental determinism

Climate is a major component of the environment, gave rise to climate determinism

Physiological responses

  • Human body temperature is around 98.6F (37C) balanced by body’s heat loss and heat gain.

    Loss: radiation, conduction, evaporation of moisture from the skin surface

    Gain: absorption of long-wave and short-wave radiation, conduction from the surrounding air

Basic concepts


Wavelength, frequency

Shortwave radiation: solar radiation composed of Ultraviolet radiation (<0.4um), visible light (0.4-0.7um), and infrared (>0.7um)

Longwave radiation: earth’s radiation.

Relationship between air temperature and wavelength

Wien’s law: 2897/T (in Kelvin); the higher the air temperature the shorter the wave length radiated

Impact of radiation on people

  • UV-C: most damage, absorbed by ozone in stratosphere

  • UV-B and UV-A arrives the earth’s surface

    Radiation determines the effects of thermoregulation and photochemical responses that occur in the skin

  • Production of vitamin D, necessary for the prevention of bone disease

  • Sunburn, red and blistering (dilating chemical), may lead to aging and skin cancer Table 7.4;7.5)

(3) Seasonal affective disorder (SAD):

mood disturbances related to season (related to too much or too little solar radiation). Example: winter depression. Sadness, decreased physical activity, weight gain, decreases libido, interpersonal conflict. (light therapy or drug)

Basic concepts (continue)

Conduction: energy transfer directly from molecule to molecule by contact one another

Convection: energy transfer by mixing of molecules with different temperature


Latent heat (LE): energy stored in water by changes in phase

Sensible heat (H): energy transfer is measured (reflected) in temperature change.

Net radiation (Q)=LE+H

Water vapor

Dew point temperature: temperature to which a parcel of air cools to condensation

Saturation: air is holding the maximum moisture at the give air temperature (Fig 4.6)

Holding capacity increases dramatically at higher air temperature

Vapor pressure: the weight of vapor over a unit surface

Relative humidity: (vapor-pressure-in-air/saturation-vapor-pressure)*100%

How close the air to saturation

Human responses to extreme temperatures

Biometeorological Indices

Serve to predict various responses to the sensation of warmth and to assess the physiological strain imposed by combined atmospheric variables

2 most common indexes for heat are:

  • Apparent temperature (AT)

  • Heat stress Index (HI)

Signs of heat stroke:

(a)Cessation of perspiration cooling mechanisms

(b)Raising body T near 110F

(c)Skin becomes dry and hot pulse become rapid and irregular

Windchill: coined by Antarctic explorer Paul A Siple to describe the cooling power of wind for various combinations of temperatures and wind speed


First in Antarctic to measure the rate of freezing of water at various temperature and wind speed

Then modified windchill formula to include the effect of clothing variables of breathing and heat transfer through clothing

Model assumptions: a healthy adult (1.7m height, body surface area 1.7m2) walking outdoors at 1.33 m/s will to generate 188wm-2 of heat

To main thermal equilibrium, amount of heat loss must not exceed the amount of heat generated. The balance is achieved by wearing an appropriate thickness of clothing

Windchill advisories are based on the sensation of cold felt by the majority of people

Low Temperature impact: Windchill index

(To predict frost bite)

Windchill index

Climate and Health

Climatotherapy: the utilization of prevailing climate as therapeutic

“escape weather”-travel for climate (Summer palaces, Mediterranean yachts, Florida homes)

Intense heat stresses circulatory system;

Cold , damp weather cause depression and circulatory problems

Diseases of respiratory system are worsened in places with high airborne particle counts (asthma, bronchitis, tuberculosis).

Morbidity and Mortality

Incidence of asthma increases markedly with onset of cold weather; respiratory disease occur much more in winter than in the summer (older and very young people are more vulnerable)

Heatwave and mortality

This graph tracks maximum temperature (Tmax), heat index (HI), and heat-related deaths in Chicago each day from July 11 to 23, 1995. The gray line shows maximum daily temperature, the blue line shows the heat index, and the bars indicate number of deaths for the day.

Impact of other extreme weather events on human health

Direct impacts: injury and death by storms, flooding, etc

Secondary impact: changes in ecosystem (bacteria, fungus etc); in public health infrastructure (availability of safe drinking water); mental problems (post traumatic disorder)

Stratospheric Ozone and UV radiation

  • Decreases in ozone in stratosphere(5-10 miles above surface) lead to increases in UV radiation on troposhere

  • During the 1980s and 1990s at northern mid-latitudes (such as Europe), the average year-round ozone concentration declined by around 4% per decade: over the southern regions of Australia, New Zealand, Argentina and South Africa, the figure approximated 6-7%. (ozone hole was detected during southern hemispheric spring over the Antarctic)

  • The groups most vulnerable to skin cancer are white Caucasians, especially those of Celtic descent living in areas of high ambient UV.

  • Culturally-based behavioral changes have led to much higher UV exposure, through sun-bathing and skin-tanning. The marked increase in skin cancers in western populations.

A more complete view of UV on human health

Indirect impacts: through infectious diseases

1. vector mosquitoes species that causes malaria, dengue and yellow fever (tropical and subtropical).

2. rodents act as reservoirs for various disease; flooding is associated with rodent-borne diseases. Other diseases associated with rodents and ticks thrive in temperate climate with wild winter.

3. Many diarrhoeal diseases vary seasonally, suggesting sensitivity to climate. In the tropics, it peaks during the rainy season. Both floods and droughts increase the risk of diarrhoeal diseases. Major causes of diarrhoea linked to heavy rainfall and contaminated water supplies.

4. food-borne infections (e.g. salmonellosis) peak in the warmer months

5. Climate affects air-pollution related diseases

Climate and Architecture

Shelter with food is one of mainstays of human life on earth.

The nature of shelter required largely depends on the conditions of the environment, climate is the most important

Primitive people used the limited resources at hand developed shelters that were in harmony with the climatic conditions under which they lived.

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