Geography. 1º ESO

2.1. The Blue Planet (continuation)

The Earth was formed 4.600 million years ago.

It is surrounded by the atmosphere, a layer of gas that filters the harmful radiations from the Sun and helps regulate the temperature.

There is liquid water on its surface.

The temperature is moderate.

2.2. The Earth’s characteristicsShape:

The Earth is an imperfect sphere, wider at the equator (40077 km) than at the poles (40009 km).

Dimensions:

The surface of the Earth is 510 million km2, about 1000 times the size of Spain. (Also see page 7)

The Earth’s movements: Rotation: Is the turning of the Earth around its imaginary

axis.

Revolution: The movement of the Earth around the Sun is called a revolution.

2.3. The Cardinal PointsThe four cardinal points help us to locate

specific places on Earth. - North- South- East- West

3. Rotation of the Earth: days and nightsThe Earth rotates constantly on its axis in a

west-to-east direction. It takes nearly 24 hours.

3.1. Consequences of rotationThe alternation of day and night: the Sun

gives light and warmth to one side of the Earth, while the other side remains in darkness and cools down.

So, Why is rotation important for life on Earth?

3.1. Consequences of rotationThe apparent movement of the Sun: at

dawn/sunrise the Sun ‘appears’ in the East and at dusk/sunset it ‘disappears’ in the West. In fact, it is the Earth that is moving, not the Sun.

Time Zones: This movement causes the progression of days and nights. When it is night-time in some places, it is a day-time in others. In order to establish an official time in every country, the Earth’s sphere (360º) is divided into 24 time zones that have a separation of 15º (360º÷24 hours = 15º). Every place that is situated in the same time zone has the same solar time.

3.1. Consequences of rotationTime Zones (continuation)

Taking meridian 0º (Greenwich) as our reference point, we put the clock forward one hour for every time zone we move towards the east and put the clock back one hour for every time zone we move towards the west.

Some countries in two time zones have the same time for the whole country (e.g. Argentina). Others have several time zones (e.g. USA).

[You have a very good map about this in your book]

Time Zone ActivitiesObserve the map with the time zones and

consider: if in Madrid it’s 13:00, what’s the time in New York? And in Moscow?

Why is it an hour earlier in the Canary Islands than in Madrid?

Why do you think Spain has not the Greenwich time?

Where does the Sun rise first in Spain?

4. Revolution of the Earth: SeasonsThe movement of the Earth around the Sun is called

a revolution.

Revolution is the west-to-east orbit of the Earth around the Sun.

It takes 365 days, 6 hours, 9 minutes.

Because each year has 365 days, those 6 hours are accumulated and every four years February has an extra day. The years with 366 days are called leap years.

The Earth’s axis is not perpendicular but is tilted at an angle. This inclination causes the different seasons: different areas of the planet are exposed to different amounts of solar light during the year.

4.1. Consequences of the Earth’s revolution The seasons of the year

Due to orbiting and the inclination of the Earth’s axis, each of the two hemispheres has a different exposure to the Sun’s rays:- In summer the rays fall directly on one hemisphere, while the other receives them with a strong inclination, making it winter. - In spring and autumn the rays fall on both hemispheres with the same inclination. When it is spring in one hemisphere it is autumn in the other.

Different duration of nights and days.

The different climate zones: Depending on the latitude, the Sun’s rays fall

with a different inclination. We can distinguish: One warn zone. Two temperate zones. Two cold zones.