Grade -8 (Science ) :- Weather and Climate

               Unit :- 20       Weather and climate

Weather (Mausam):The specific atmospheric condition of a particular place at a particular time is called weather .For example :Atmospheric condition of a place in the morning ,at the noon , and in the evening may be different .Weather is small component of climate .The study of weather is called meteorology . Weather is measured by the following instruments : i)Thermometer    ii)Rain gauges    iii)Barometer  iv) Anemometer

Climate (Hawapani):-The average atmospheric condition of a place over a long period of time is called climate .

Or

The average weather pattern of a place over the whole year is called climate .

Division of climate .A)The world is divided into 5 main climate zone or region on the basis of altitude  .They are

i)Tropical climate :(Uashan)The height of 60m -1200m from sea level

ii)Sub tropical climate :The height of 1200m -2100m meter from sea level .

iii)Temperate climate .(Sumsitosan)The height of 2100m -3300m from sea level .

iv)Cold climate (Sit):The height of 3300m – 5000m from sea level .

v)Tundra climate (Sit):(Polar /alpine) :The height of above 5000m from sea level .

B) The world is divided into 8  main climate zone or region on the basis of the nature of rain fall  .They are

i)Equatorial climate  :Rain fall in all season

ii)Tropical climate :Summer rain and winter dry

iii)Semiarid tropical climate zone :Slight summer rain

iv)Acid climate zone :Dry in all season

v)Dry Mediterranean climate zone :Slight winter rain summer dry .

vi)Mediterranean climate zone : Winter rain and summer dry

v)Temperate climate : Pericipition in all season   

vi)Polar climate :sparse in all season

Factors affecting climate :The major factors that effects the climate are as follows .

i)Distance from the equator or latitude

ii)Height from the sea level

iii)Slopes of mountains

iv)Distance from the sea

v)Oceanic center

vi)forest and vegetation

vii)River and lakes

viii)Local wind

xi)Human activities

Climate of Nepal :On the basis of latitude(Achhans) ,Nepal lies in the tropical monsoon climate  region but

 A)On the basis of altitude (Height) There are following different types climate in Nepal :

i)Tropical climate :The height of 60m to 1200 m from sea level i.e. terai region. The land of this area is fertile and consist of tropical evergreen forest .

ii)Sub- tropical or moderate climate :The height of 1200m to 2100m from sea level i.e. valley or river basin .The land of this area consist of desidous  vegetation .

iii)Cool temperate climate :The height of 2100m to 3300m from sea level i.e.Mid hill region .The land of this area consist of coniferous forest .

iv)Cold climate :The height from 3300m to 5000m sea level  from sea level i.e. higher altitude .The land of this area does not consist of any vegetation .

v)Tundra climate :The height of above 5000m from sea level i.e. Himalaya region .The land this area does not consist of any vegetation .

B) On the basis of influences of wind in Nepal There are following types climate :

i)In summer rain falls occurs due to the influence of moist summer monsoon wind that comes from Bay of Bangal(Bangal ko Khadi) .

ii)Winter is dry due to the influence of dry winter monsoon that comes from central Asia .iii)Some rain falls during winter due to influence of west air which come from Miditerranean sea(Madhay sagar) .So winter rain in Nepal is more in the west and less in west . Similarly in Nepal maximum rain falls in the Pokhara valley due to its high hill in north west and its south east part is opened and Minimum rain falls in Manang lies just northern slope of some hill that place . 

Monsoon :The periodic or seasonal wind which may be dry or wet is called monsoon .  

           
Advantages of monsoon :

i)It maintains the temperature of land .

ii)It help to increase forest which is very important for the balance of nature .

iii)It increase the water level in river and lakes which helps in boating.

Disadvantages  of monsoon :

i)It causes of landslides in hilly region and causes of  great loss of life and property .

ii)It causes of flood which destroys life and property and development of infrastructure i.e.bridge, road etc.

Methods to minimize the adverse effect of monsoon :

i)Conservation of forest and afforestation should be done .

ii)Land should not be left uncultivated .

iii)Random road construction on hill should be controlled .

iv)Wetland and watershed must be conserved .

Doldrum :The region of earth surface 30⁰C N to30⁰C S are called dodrum .This region receive the  straight sun rays so, it have maximum temperature .

Polar region :Polar region of earth never receive straight sun rays so such region are always covered with snow ,therefore it have minimum temperature .

Distance from sea level and climate :The place have more distance from sea level ,there is very cold in winter and very hot in summer

Height from sea level and climate :The place have more height from sea level ,temperature decreases according to increase of height .