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
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
Loss: radiation, conduction, evaporation of moisture from the skin surface
Gain: absorption of long-wave and short-wave radiation, conduction from the surrounding air
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
Radiation determines the effects of thermoregulation and photochemical responses that occur in the skin
(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)
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
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
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:
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)
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).
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.
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)
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
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.