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  2. About the Chairman

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  3. About the Chairman

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  4. Exhausting Glacial Lakes of HKH before they explode
    By Muhammad Raza KhanChairman APM PakistanDec 2012
    Many disastrous floods have occurred in the...

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  5. Article By Chairman APM - Badaltay Mosam (The Changed Climate)

    By Chairman APM

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  6. Understanding Global Climate

    By Muhammad Raza Khan

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  7. World Precipitation Regions

    By Muhammad Raza Khan

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  8. Nature Strikes Back... Wake up call

    Raza Khan
    Chairman APM
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  9. NAO and The Sunspot Theory

    Mohammad Raza Khan
    Chairman APM - 2010

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  10. Climate change led to catastrophe
    Article by Chairman APMRaza Khan
    11 August , 2010

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  11. Before Its Too Late

    Author: Muhammad Raza Khan (Chairman APM)

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  12. Iceland Volcanic Eruption

    By Muhammad Raza Khan

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  14. Interview with The Chairman
    Conducted by:Muhammad Waseem AbbasiVia:TeleconferenceDate:28 May 2010Time:3pm (UK); 8pm (PK)

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Understanding Global Climate

By Muhammad Raza Khan

Chairman APM - 2010


In the broadest sense, climate is the characteristic condition of atmosphere near the earth surface at a given place or over a given region.


The Average Weather conditions of a sizeable area of the earth surface over period of time (usually at least 30 year).

Elements to Generate Climate

  1. Radiations
  2. Temperature
  3. Atmospheric Pressure & Winds
  4. Humidity
  5. Clouds
  6. Precipitation & Evaporation
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These elements are directly dependent on certain factors like, latitude, altitude, distribution of landmasses and seas, oceanic currents, soil, vegetation and configuration of the land.

Net Radiation to Classify the Climate

The difference between incoming short wave solar radiation and outgoing long wave terrestrial radiation define the climate of a given area. The sun radiation is maximum on the equator. While, according to the position of the earth’s rotational axis, on the either pole it remains minimum.

Solar radiation is the gain of heat from the sun and terrestrial radiation is the loss of heat from the earth surface through which our planet gets cooling effect.

Temperature to Classify the Climate

Temperature is a key factor to generate weather of a given area. The uneven distribution of incoming solar energy around the globe is because of earth’s spherical shape and tilt in its rotational axis.  So resulting temperatures are significantly different at different places on the earth. Using monthly mean low air layer temperature, three major climate groups can be defined as follows;

  • Winterless climate
  • Mid Latitudes climate
  • Summerless Climate of High Latitudes

The Winterless climate of the low latitudes is usually defined as one in which no month of the year has a monthly mean temperature lower than 64.4 degree Fahrenheit (18° Centigrade).

The mid latitudes have both a summer and a winter season across a year.

Summerless climate is commonly defined as one in which no month has monthly temperature higher than 50°Farenheit (10° centigrade). It has wide latitude range in the Northern Hemisphere, being farthest pole-ward over the landmass of North America & Russia, but dipping to mid latitudes over the intervening oceans. The 50° F (10°C) isotherm of the warmest month closely coincides with the northernmost limit of tree growth, hence it separates the regions of Boreal Forests from treeless Arctic Tundra. Climatologically, here thermal boundary defines the limit of the natural boundary of vegetation.

Precipitation (ppt.) to Classify the Climate

The relationship between world pattern of precipitation (ppt) and air masses source regions and prevailing air masses is very important in the climate sciences. Average yearly ppt. is used on a world map by means of Isohytes .Isohyets means rainfall. Iso is a Greek Prefix mostly used before names of several physical quantities to present as lines on a graph in daily sciences. For instance, to read a climate graph one has to be familiar with the following terms:

  • Isobar means Atmospheric pressure
  • Isobaths means Depth
  • Isohaline means Salinity
  • Isohel means sunshine
  • Isohype means height
  • Isoneph means Cloudiness
  • Isoryme means Frost
  • Isoseismal means Earthquake Intensity
  • Isotach means Wind Speed
  • Isotherm means Temperature
  • Isogon means Magnetic Variations

For regions where all or most of the precipitation is rain we use the word ‘rainfall’ and for snowfall regions we use the word ‘precipitation’. There are at least seven precipitation regions in the term of annual total in combination with location.

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