Weather, Climate and Pressure

Africa map

What is the difference between the Northern part of Africa and the Southern part ?

What are the geographical features of the Northern part?

What are the geographical features of Southern part ?

So what does the Difference show ????

The reason ….

Geographically Africa is divided into two Hemispheres, Northern hemisphere and Southern hemisphere as the Equator passes through the continent. Thus Sahara is in the North and Grasslands lie in the South. This diversity is brought about by the Geography. The climate of a region is influenced by the Geography.

Thus geographically which are the different regions ?

What climate do we find in deserts, mountains, frozen lands , plateaus , plains, coastal lands ??????

Why is there difference in climate in these regions ??????????

Differences in Climate !!!

Climate ??

Climate is the weather of a place averaged over a length of Time. (approx 30 yrs)

That’s why climate varies from place to place, creating a variety of Enviroments.

Climate changes with time.

Climate changes with Human activity – Like burning of Coal, Natural gas, fossil fuels.

Climatologists – Scientists who study Climate

They also study the changes in climate.

This area of study is very important to

us ????????

Can you tell WHYYYYYYYY !!!!!!!

Global Distribution of Climate

Tropical : Places located on the Equator

These also have equatorial climate. These Places are Hot all around the year and rains everyday. (avg temp is 27 degree C)

Tropical Grassland :

These places are also known as Savannah. It is Hot all around the year, has wet and a dry season. (Avg Temp is 25 degree C)

Desert Climate :

These places are very hot around the year. Rainfall is unrealiable. (Avg Temp is 30 degree C, It may rise upto 50 degree C and falls below 0 degrees at night)

Mediterranean Type of Climate :

These places are hot in summer and mild in winter. It rains mainly in winter. (Avg temp is 25 degree C in summer and 13 degree C in winter )

Continental Interior :

These places are hot in Summer and cold in Winter. It rains mainly in summer. (Avg temp in summer is 20 degree C and in Winter is -15 degree C)

Temperature Maritime :

It is warm in Summer and mild in winter. It rains around the year. (Avg Temp in Summer is 16 degree C and in Winter is 7 degree C)

Tundra Type :

These places have Short and Cool summers and Long and Cold Winters. (Avg Temp in summer is 3 degree C and in Winter is -28 degree C)

Match the Columns

a. Very hot and dry all year 1 Tropical

b. Hot all year and rains everyday 2 Tropical grassland

c. Cool in summer and very cold in winter. 3 Desert

d. Hot all year with a wet and dry season 4 Mediterranean

e. Hot in summer and mild in winter 5 Continental interior

f. Hot in summer and cold in winter 6 Temperature Maritime

g. Warm in summer and mild in winter 7 Tundra

Factors Affecting Climate

Latitude :

Solar energy is concentrated at the Equator. This explains why Tropical climates are always hot.

Towards the North and South Poles solar energy is spread out and is filtered by its longer, oblique- angled journey. (slanting rays). This explains why it gets colder towards the North and South Poles.

Altitude :Altitude is the Height above sea levelThe solar energy (heat) is absorbed by

gases in the atmosphere. The atmosphere becomes thinner as altitude increases. This means that temperature falls by 6.5 degree C for every 1000m

High land causes rainfall

Prevailing Winds :

Polar winds bring cold weather

Tropical winds bring warm weather

Sea winds bring precipitation (rainfall )

Land winds bring dry weather

Distance from the sea :

The sea has a moderating influence over the climate

In summer it takes a long time to heat up – cooling the surrounding area.

In winter the sea takes a long time to cool – warming the surrounding area.

Warm ocean currents flow from tropical areas warming the surrounding areas

Cool ocean currents flow from the poles. They lower the temperature and bring Fog.

True or False

Solar energy is concentrated at the North and South Pole.

The atmosphere is thinner at the top of the mountain.

High land receives more rainfall.

Winds blowing form the sea bring dry weather

The sea winds bring rainfall.

Cool ocean currents cause Fog.

Tropical winds bring warm weather.

What does this Picture show ?

This is Weather Forecast Why do we need Weather forecasts ????To decide what to wear when we plan for trips,

to avoid / avert dangers

Weather is the state of atmosphere at some place and time.

How is weather information collected ?Find out ??????

The Facts..

Earth is not the Only Planet with a variety of weather conditions.

For Eg : Titan, a natural satellite of Saturn also has Atmosphere.

Weather also affects the agriculture, transportation, industry and delays flights.

Do you know HOW ?????

Winter snows and Fogs delays transportation and Flights.

Weather affects agriculture as in todays days we don’t know how the weather will be like ?????????/

Why are we so unsure of weather?????

Has weather affected Human Life ?

What causes Weather ???

Weather takes place in Atmosphere, the layer that surrounds the Earth. Air is a mixture of gases and suspended particles (dust).

Nitrogen is available in large number

78 %

Oxygen is 20 %

Other gases constitute 1 %

Pie Diagram

The other gases also play a vital role in Earth’s Atmosphere

Eg Water Vapour is an invisible gas but without this gas there would be no clouds , no rain, no snow, not even plants and animals.

Ultimately What would it Affect ???????

Parts of Atmosphere !!!

Most of the weather occurs in the lowest part of the Atmosphere. (Troposphere )

How is the atmosphere held around the Earth ?

The force of gravity pulls the gases of the atmosphere towards the Earth and prevents them from escaping into space.

Types of Weather

Temperature :

describes how hot or cold is the air.

Precipitation :

describes any type of water falling from the atmosphere, includes rain, snow, hail.

Air Pressure :

describes the weight of air. Warm air rises causing low air pressure. Cool air sinks causing high air pressure.

Wind :

The movement of air from one place to another. Wind blows from high pressure to low pressure areas.

Humidity :

Actual amount of water vapor in the atmosphere.

Clouds :

Tiny water droplets in the atmosphere.

Questions

What is weather ?What is wind ?What is humidity ?Find out the instruments to measure :TemperaturePrecipitationAir pressureWindHumidity

What is this

instrument called

Why do we have seasons ?

The Four seasons – Spring , Summer, Autumn and Winter are caused by the tilt of the Earth’s Axis. As the Earth moves around its axis, different parts are tilted towards the Sun for a few months at a time. The part leaning towards the Sun has Summer, while the part leaning away from the Sun has Winter.

Find out the hottest and Coldest place on Earth ?

How many countries have two seasons ?

What kind of climate does Antartica have Why ?

Greenhouse effect

What is greenhouse Effect

The Greenhouse effect is caused by cars, factories and power stations, releasing gases like carbon dioxide into the atmosphere. Like a house these gases trap the heat and gradually make the climate warmer.

Reflection

Is today’s climate changing?

Is it different from the climate which existed 5 years ago ?

Prepare a Questionnaire to ask a person from the weather department ?

Also prepare what could be the possible reasons?

Sea breeze

Have you noticed that people go to seaside on hot sunny days – to enjoy the cool sea climate. These breezes are caused due to the difference in temperature between land and sea. The land and the sea heat up at different levels.

Sea breeze

Sea breezes are light winds that travels from sea to land.

During the day the land warms up quickly. Comparatively the sea warms up more slowly. In summer the difference in temperature between the sea and land is quite big. This helps the winds to move. The warm air over the land rises and the cool air of the sea replaces it.

Land breeze

At night the land cools down faster than the sea. The air above the sea is warmer than the land and it rises creating a low pressure area. Thus the breeze form the land moves to the sea.

Related topics

Is there a hole in the Ozone layer ? How did it come about ?

Can we stop some of the climatic changes ? Or is it too late ? If yes , then How ?

How will the future be affected by Man’s activities ? Is there a bright and healthy Future ???????????????????

References :

• Wind and Air Pressure – Allan Rogers and Angella Streluk , Heinemann , 2002, Oxford

• 100 questions and answers on World’s Climate and Weather - Dick File et all Navneet, 1995, Mumbai