UNIT 4. THE ATMOSPHERE. MANUEL DE FALLA 2018-201

HERE YOU HAVE A PART OF THE CONTENTS THAT ARE GOING TO BE A PART OF THE NEXT EXAM. REMEBER THAT YOU ALSO HAVE TO STUDY A PART OF THE UNIT 7. THE PREHISTORY.

 

1. THE ATMOSPHERE AND ITS CHANGES.

1. 1. Functions and composition of the atmposphere.

Atmosphere: gaseous layer that surrounds the Earth.

Composition: is made up of water vapour and a mixture of gases:

• nitrogen, 78%
• oxygen, 21%
• ozone.
• carbon dioxide.

Its makes life on Earth possible because:

• it provides gases that are essentials to life (oxygen).
• it filters dangerous solar radiation
• it regulates the planet's temperature.
• it protects the planet from the impact of meteorites.

1. 1. Atmospheric phenomena. Weather and climate.

We have to distinguis between the atmospheric weather an the climate.

• Atmospheric weather is the state of the atmosphere over one place at a specific time. The weather is changeable and can be different every day. This is because the troposphere is divide into large air masses that are moving continuously over the Earth's surface.

The science that study the weather is meteorology.

• The climate is the average state of the atmosphere over one place during a long period ot time. It is calculated observing the succession of types of weather for at least thirty years. Is more stable than weather.

The science that study the various types of climate is climatology.

2. THE  ELEMENTS OF CLIMATE (I) TEMPERATURE AND PRECIPITATION.

 2.1. The elements of climate.

Elements of climate: components of the atmosphere that can be measured. The main are:temperature, precipitation atmosheric pressure and wind.

Temperature and its factors.

Definition: temperature is the amount of heat in the air. It is measured in degrees Celsius (Cº), using a thermometer.

Temperature is determined by the following factors:

• Latitude. Between the Equator and the Tropics the temperature is always high because the rays of the Sun reach the Earth surface almost perpendicular, while in the Poles the solar rays reach the surface with an oblique angle.
• Altitude. The temperature drops 0.6ºC for every 100 metres above sea level, because the air is less dense and due to this conserves less heat.
• Distance from the sea. The sea waters change its temperature slower than the land, because of that temperatures are milder on the coast.Distance from the sea.

Also, we can distinguish different latitudinal thermal zones:

• One torrid zone, between the Equator and the Tropics.
• Two temperate zones, between the Tropics and the Polar Circles.
• Two frigid zones, around the Poles.

Isotherm: imaginary lines that connect locations with the same temperature in map.

Precipitation and its factors.

Precipitation: water that falls on the Earth's surface from the clouds, either in liquid (rain) or sold (snow and hail) forms.

It is meassured with a pluviometer and it is calculated in milimetres (mm).

There are several factors that determine precipitation:

• Latitude. Precipitation levels are higher at the equator.
• Altitude and terrain. Precipitation levels rise in relation to increase of altitude.
• Distance from the sea. Precipitation levels are higher on the coast because the sea is a constant source of humidity.

3. ELEMENTS OF CLIMATE (II). ATMOSPHERIC PRESSURE AND WIND.

3. 1. Atmospheric pressure and its factors.

Definition.

Atmospheric pressure is the weight of a column of air on a place. It is meassured with a barometer and is expressed as millibars (mb).

The average atmospheric pressure meassured at sea level it is 1.013 mb, but the atmospheric pressure changes and it is higher or lower in different areas because of two factors:

• altitude, the higher the altitude, the smaller the volume and weight of the column of air over a location becomes.

• air temperature:

1.  cold air is denser and heavier, so its tends to fall. As a consequence, its warmed and produces dry and estable weather, and zones of high pressure known as anticyclones
2. warm air is lighter and less dense, so it tends to rise, then cools and produces precipitation. As a consequence produces zones of low pressure known as depressions.

Weather maps.

A weather map is a chart that represent meteorological conditions over a specific area at a specific time. In a weather map appear the following elements:

• isobars, lines that connect all the points of equal atmospheric pressure.
• anticyclones are represented with a capital A (usually are also represented with an H, high pressure). The wind moves between the isobars from left to right in the northern hemisphere and from right to left in the southern hemisphere.
• depressions are represented with a capital B  (usually are also represented with an L, low pressure). The wind moves between the isobars from rigth to left in the northern hemisphere and from left to right in the southern hemisphere.

• fronts, areas of contact between two air massess with different characteristics. Can be:

1. hot fronts, represented with a red line with semicircles.
2. cold fronts, represented with a blue line with triangles.
3. Occluded front, represented with a red line with semicircles and triangles (is the meeting of a hot and a cold front). In this case, the front is about to dissapear.

Wind and its factors.

Wind is the horizontal movement of air.

Measurement: 

• its speed is measured in kilometres per hour (km/h) or in metres per second (m/s), using a anemometer.
• its direction is determined by the cardinal point of the source of the wind: east wind, north wind. Is measured using a weather vane.

Wind is caused by the difference in atmospheric pressure. The wind blows from areas of high pressure towards areas of low pressure.

On Earth we are going to find:

• constants winds that maintain an equilibrium of temperatures, transporting hot air towards the cold zones and vice versa. The most important are the trade winds (in spanish: alisios) which goes from the Tropics to the Equator, the west winds and the polar winds.
• seasonal winds, such as the monsoons (in spanish: monzones) in South East Asia
• daily winds, such as marine and mountains breezes (in spanish: brisas).

 

4. THE BIOCLIMATIC ZONES. VEGETATION.

The climate and climatic zone.

The combination of the temperature, precipitation, amospheric pressure and wind creates the different climatic zones. A climatic zone is a division of the climate of the Earth according to average temperatures and average rainfall (precipitation level). We can distinguish the following climatic zones:

• Torrid zone, which includes the equatorial and tropical climates.
• The northern and southern temperate zones, which includes the mediterranean, oceanic and continental climates.
• The northern and southern frigid zones which includes the polar climates.

Also appear azonal climates that can be found in different regions: deserts and mountains.

Vegetation and biosphere.

Vegetation: is the entire range of plant life in an área. It is a part of the biosphere.

Biosphere: is the combination of all living beings on the planet and the enviroment they live in. It is formed by the troposphere, the Hydrosphere and the litosphere.
The main characteristic of the biosphere is its enormous diversity of plant and animal species (biodiversity). Plants are organised in vegetal formations.
A vegetal formation is the combination of plants in a región that are similar in size of characteristics. We can distinguish three types of vegetal formations:

• Forest areas are formed by trees. A tree is a plant which has a clearly defined trunk and is tall (usually more than 8 metres of height).
• Scrubland consist of bushes. Bushes are smaller than trees and have not trunk. Its branches divide at ground level.
• Grasslands consists of grasses.

The distribution of the vegetation is conditioned by numerous factors:

• the relief
• the soil
• the climate (humidity, light, temperatura and wind).

The Earth's bioclimates.

Earth is divided in several bioclimatic enviorments or bioclimates. A bioclimate is a extensive región characterised by its own climatic features and vegetation. We can distinguish three major bioclimates:

• the torrid bioclimate.
• the temperate bioclimate.
• the frigid bioclimate.

Weather map.

ELEMENT OF CLIMATE	DEVICE	UNIT
TEMPERATURE	Thermometer	Degrees celsius
PRECIPITATION	Pluviometer	Milimeters or mm
ATMOSPHERIC PRESSURE	Barometer	Milibars.
WIND	Anemometer	Meters per second or kilometers per hour