SOLAR ENERGY, TEMPERATURE AND CLIMATE

 

 1.   Weather refers to the condition of temperature, wind, pressure and precipitation at a place at a given time. It changes rapidly and sometimes do so in less than an hour.

 2.   Observations of the weather elements at a particular place over a period of 35 or more years provide us with a description of its Climate. 

 3.   Climate is therefore the average weather conditions of a place. Unlike the weather, a climate changes gradually.

 4.   The scientific study of the varieties of climates of the earth's surface both past and present and their distribution is termed as Climatology.

 

Elements of Weather and Climate:

             1.    Insolation (Temperature)           2.  Precipitation (Moisture)

3.  Winds                                            4.  Pressure

 

Climatic Controls

             1.    Latitude:                              2.  Land and Water Contrasts:

3.  Ocean Currents:                  4.  Altitude (Height)

5.   Landform Barriers:            6.Human Activities

 

The Heat Budget:

The energy budget depicts the inflow and outflow of solar energy throughout space, the atmosphere and on the earth's surface.

a)   About 26% of total solar energy is Reflected

b)   8% of the sun's energy is Scattered 

c)   20% reaches the earth's surface as Diffuse radiation

d)   About 27% of solar energy reaches us as direct radiation

e)   19% of the energy from the sun is absorbed by the ozone

      water vapor, carbon dioxide, solid particles and methane

 

Factors causing Changes in Local Energy Budget (factors)

1.  Latitude,                     2.  Presence of water vapor

3.  Urbanization               4. Land/water distribution.

 

Heat Transfer Processes:

a) Conduction      b) Convection  c) Advection   and  d) Radiation

 

Latent heat of Vaporization and Condensation:

Solar energy absorbed in evaporation is stored in water vapor as Latent Heat of Vaporization. Later, water vapor may cool to form liquid water through a process called Condensation. The energy released through the condensation process is known as Latent Heat of Condensation

 

Different Types of Heat:

 

a) Sensible Heat: The heat detected by the human senses.

b) Latent Heat:  The hidden heat stored in water vapor

c) Specific Heat: Amount of heat required to raise a substance's temperature by a given amount.

 

AIR TEMPERATURE AND HEAT

 

Temperature is a measure of the degree of heat or cold in a body. The scales for measuring temperature includes:

 

1. Kelvin Scale:  Used primarily by chemists and physicists

2. Fahrenheit Scale:  Devised in 1714. By this scale, water boils at 2120 F and Freezes at 320 F.

3. Celsius scale (Centigrade) was devised in 1742 by a Swedish Astronomer. Water freezes at 00 C and boils at 1000 C

 

Vertical Distribution of Temperature

 

a) Normal Lapse Rate: Vertical reduction in temperature with

increases in altitude is known as the Normal or Environmental Lapse Rate. (60C drop for every 1000 meters or (3.60 F drop for every 1000 feet). 

 

b) Temperature Inversion: 

A condition in the atmosphere during which temperature increases with increasing altitude. There are several types of inversions:

i)    above surface inversion common at latitudes 30 and 35

ii)   surface inversion occurs when the earth cools off rapidly in the night so that at dawn,

       warm air overlies cool air.

iii)  Inversion occurs when cool air blow to cover warm surface of some water body.

 

GLOBAL WARMING:

 

Global average temperatures increased steadily from 1880 to 1940, fell slightly between 1940 and 1975 and have risen sharply since 1975.

 

Global warming refers to human-induced increases in the average global temperatures near the earth's surface caused by concentrations in the atmosphere of some green house gases, notably Carbon dioxide, Methane and Nitrous Oxide.

 

Green House gases.

Gases in the atmosphere that allow solar energy (short wave) to reach the earth’s surface but traps the re-radiated heat energy (long wave length) causing the atmosphere to heat up. They include water vapor, Carbon Dioxide, Methane and Ozone. The Green House effect is the atmospheric warming that results from the passage of incoming short-wave energy and the trapping of the outgoing long wave energy by the green house gases.

 

            1.   Carbon Dioxide increases through burning of fossil fuels (coal, oil and natural gas) and deforestation.

            2.   Methane is formed by decaying organic matter (landfills and the digestive systems of cattle).

            3.   Nitrous Oxide is mainly produced from burning coal

 

POSSIBLE EFFECTS OF GLOBAL WARMING

 

1.   Thawing of Ice found at the North and South Poles:

2.   Rise in Sea Levels and possible relocation of People 

3.   Changes in Climatic Patterns  & Changes in human activity

4.   New Diseases, Pests and Sicknesses

 

DEALING WITH THE THREAT.

 

Different Viewpoints have been expressed

1.  No Threat so let us do nothing Strategy

2.  Wait and See Strategy

3.  Take Precaution Strategy