The Earth is a watery planet because oceans cover over 72 % of its
surface. It is made up of rocks, water and air. It has life on it. The
earth is moving all the time
The EQUATOR is an imaginary line that divides the earth
into two equal halves. It goes right around the earth like a
belt that is tied around your waist. It divides the earth into
Northern Hemisphere & Southern Hemisphere.
The top- most tip of the earth is the North Pole. Directly
opposite is the southern-most tip called South Pole. The
Axis is an imaginary line that connects the north pole &
the south pole & the centre of the Earth.
Like the other planets, the
Earth spins like a top on its
axis. We call this movement
Rotation is the daily
movement of the earth on its
axis from West to East. It
takes 24 hours to complete
one rotation. This equals one
day and one night. Rotation
of the earth causes day and
Rotation of the Earth causes day and night. The side of the
Earth that faces the sun has day. The opposite side has
night. Rotation always takes place from west to east.
The Earth also moves around the sun in a set path
called the orbit. The movement of the Earth
around the sun is called Revolution. It takes 365
days & 6 hours to complete one revolution. This
equals one year. The revolution of the Earth causes
The revolution of the Earth around the sun causes seasons. We have
different seasons in a year-summer, rainy, winter, autumn and
spring. The axis of Earth is tilted a little. As the Earth revolves, the
pole and the hemisphere of the Earth that is tilted towards the sun is
warmer and has summer. The pole and the hemisphere which is
tilted away from the sun this time has winter as it gets less heat.
Different places on the Earth get different amounts of heat. This
causes changes in the condition of the air from time to time and
place to place. The condition of the air at a given time and place with
respect to hotness or coldness, wind, rain, sunshine, etc. is known as
Climate is the average picture of weather conditions in a
place over a long period of time. Meteorologist study the
weather conditions of a place and the seasons it has for at
least thirty years before deciding what the climate of the
place is. The temperature of the air and the wind pattern
are two important factors that causes the change in
seasons and climate of a place.
Sea breezes are winds that are caused by the differential heating rates of land
During the day the land heats up more rapidly than the sea because:
•land has a lower specific heat than water - it requires less heat to raise the
temperature of 1 kilogram of earth by 1 degree than it does for water;
•the incoming heat warms a shallower layer of the land because earth is a poor
conductor of heat. In water the heat is spread through a significant depth by
conduction, convection and forced mixing.
Warm air over the land rises creating a lower pressure at the surface and a
higher pressure at the altitude that the air is lifted to. Cool air from over the
sea which is now at a higher pressure tends to move in to the low pressure
area over land. A circulation is established as the air over the sea subsides and
warm air from over land moves in to take its place.
During the day the land gets heated up faster than the sea. Thus the cool air
from the sea blows from the sea towards the land causing sea breeze.
During the night the land gets cooler up faster than the sea. Thus the cool air
from the land blows from the land towards the sea causing land breeze.