Unit 4. Climate

1. Climate’s Elements

The Weather

• Weather is the present condition

• Weather can varied over shorter periods.

• It is studied by the meteorology.

The Climate

• Climate is the term for the average atmospheric conditions over longer periods of time (usually over 30 years).

• It is studied by the climatology.

The Weather Forecast

• Thermometer• Pluviometer or rain gauge• Higrometer• Barometer• Anemómeter• Weathercock or weathervane

The weather sation:

¿which iswhich?

Activities:

Who predicts the weather?

• Meteorologists are in charge of weather forecast.

• Nowadays they use weather satellite

Compulsory essay

• Choose a place from a hot climate zone, temperate zone and cold zoneand complete the next chart

Activities:

1. Who speaks about the weather and who does it about climate?

– It rains a lot in spring in my town.

– It is very hot and sunny today. Let us go to the beach.

2. Which sentences speak about weather and which ones about climate?

– It does not usually rain in Seville in summer.

– Yesterday, there was a very heavy storm in Zaragoza.

– It is very cold in Siberia in winter.

– I heard on the radio that is it going to be very cold in Valladolid tomorrow.

1. CLIMATE’S ELEMENTS

• Temperature. It measures how hot the air is.

It can be expressed in several kinds of degrees: • Celsius (ºC). They base on the different states of

water (solid, liquid, gaseous). • Below 0ºC water freezes, • Over 100ºC water boils and turns into vapour.

• Fahrenheit (F). It is widely used in North Americaand has no relationship to states of water.

• Kelvin (K). It bases on the absolute zero (-273oC).

Thethermometermeasures thetemperatures.

They are usuallyrepresented on themaps throughisotherms.

Key Concepts:

• sum of the daily avarage temperatures and dividing them by 30

Monthly average range temperature

• Sum monthly average range and dividing them by 12.

Annual temperature

• Highest month temerature (1 month)- Lowest month temperature(1 month).

TemperatureVariation or temperature oscillation(Amplitud térmica):

• Sum of monthly precipitations

Annual precipitation

Climate factors:

Latitude

Altitude

CoastalLocation

Latitude:The sun falls on the earth in a different wayaccording to the latitude, hence the difference of

temperatures of the regions.

Altitude

• It descends as we are higher in a proportion of 0.6ºC every 100 metres (c. 1ºC every 160 m).

COASTAL LOCATION

Sea currentsinfluence over thetemperatures and make them milder.

The farther a place is from the coast the more extreme its temperatures are

CoastalLocation

ACTIVITY:

• Answer in your notebook

– 6. How does altitude modify temperature?

– 7. How does the sea affect temperatures in summer?

– 8. What is the temperature oscillation?

Precipitations

It is the water fallen from the sky in a solid (snow or hail) or liquid state (rain).

pluviometer or rain gauge

They are expressed either in millimetres (mm) orlitres/square metre (l/m2).

Precipitations factors:

Latitude

Altitude

CoastalLocation

Altitude

Coastal location and Latitude

Types of rainfall

Tipo:

Convectionalrain

Orographicrain (Foehn

effect)

Frontal Rain

IT IS IMPORTANT TO KNOW THAT…

The hot air is lighterso it rises above thecold air. As it raises, Itcools

Cold air is denserand heavier thatproduce air descents

Convectional rain (Tormentas de verano)

The sun heatsthe ground and

waterevaporates

Water vapourcools as it

raises

As the watervapour cools, Itcondenses and

form drops

The dropsform clouds. Rain falls to the Earth

Orographic (relief rain)

Humid air reaches a mountain

The air is forced to rise. It cools

Clouds form. It rains on the side of the mountain

that the humid air has reached

Frontal rain

Frontal rain occurs at the

front (orboundary)

between a massof warm air and a mass of cold air

1. A mass of hot humid airmeets a mass of cold air

Two types: Warm front rainCold front rain

2. The hot air is lighter so it rises above the cold air. As it

raises, it cools

Clouds form and it rains

Warm front rain

Cold front rain

COLD FRONT RAIN

Atmosphericpressure. Wind

Air moisture.

ATMOSPHERIC PRESSURE.

• Atmospheric pressure. It is the weight of air above the surface. In meteorology it is expressed in millibars (mb) or hectopascals(hPa).

– It is measured with the barometer.

– It is represented on the maps through isobars.

– Pressure is lower as the altitude increases because there is less air above those regions.

Air moisture. It is the amount of water vapour in the air.

When it is the relative air moistureit is expressed in percentages (%).

It is measured with the hygrometer. Cold air cannot withstand much air moisture. Instead warm air can do.

THE WIND…

Wind. It is the movement of air due to the pressuredifferences. It re- establishes pressure balance. It isexpressed in kilometres/hour (km/h).

Wind always goesfrom the high

pressure to the lowpressure

It is measured with ananemometer.

Its direction is known thanksto the weathercock or

weather vane.

2. CLIMATE’S FACTORS

All the climatic phenomena take place

in the troposphere (the lowest

atmospheric layer). The atmospheric

circulation explains why climates are different and why weather changes:

• Their characteristics depend on the source region they are originated.

• They can either be dry or humid; either warm or cold.

• They move due to the difference of temperatures, air moisture, and pressure.

Air masses. It is a volume of air defined by its temperature and water vapour content.

– High pressure:• Above 1013.5 mb or hPa it is high pressure or

anticyclone. It circulates clockwise in the northern hemisphere, whereas in the southern hemisphere it does counterclockwise.

• High pressures usually involve dry and sunny weather. It can be either cold or warm. The usual high pressure areas are the poles and the tropics.

Pressure centres. The average pressure is 1013.5 mb or hPa but the atmosphere is never stable:

– Low pressure:• Below 1013.5 mb or hPa it is low pressure or

low or depression. It circulates counterclockwise in the northern hemisphere, whereas in the southern hemisphere it does clockwise. • Low pressures involve rainy and unstable

weather. • The usual low pressure areas is the equator

and at mid- latitudes.

ACTIVITY:• Say the words that define the following items:

– The study of climate.

– The study of atmospheric phenomena.

– The layer of gases around the Earth.

– Area of high pressure.

– Water falling from the atmosphere.

– Area or low pressure.

• Answer whether it is true or false. Correct the wrong ones.

– The higher the altitude, the greater the atmospheric pressure.

– Warm air rises because it weighs less.

– When air moves from low pressure areas to high pressure areas, winds are produced.

3. CLIMATES OF THE EARTH • There are several climate zones in the

world:

– One hot zone between tropics. Itis due to the sun, which falls onthe surface vertically. • Annual temperature from

20º C and 25ºC

– Two temperate zones betweenthe tropics and the polar circlesin each hemisphere. The sun fallson the surface in an oblique way. • Annual temperatura from 5ºC

to 20ºC

– Two cold zones above each polar circle. Insolation is minimal sincethe sun falls on the surfaceextremely obliquely.

• Annual temperatura lees than5ºC

Activity: draw in your notebook climates zones.

HOMEWORK:

• Using an atlas, name five cities in each climatic zone, from the northern and southern hemispheres.

• Say in which climatic zones the following countries are located: Angola. Norway. The Sudan. Australia. Cuba. Colombia. Argentina. Iceland. South Africa. Spain.

Climographs or climate charts

Charts whereTemperaturesand precipitationsare shown in a graphic.

Look the climographs. Do you see anything weird?

and this?

What climate zone belongs the nextclimopgrah?

HOT CLIMATES

They are located between the tropicsand their average temperatures exceed18ºC. They have high insolation:

Tropical rainforestor equatorial

climateIt is located around theequator, so it is only foundin Africa, America, Indonesia and some Oceania’s islands.

Its temperatures are quite stable throughout the yearand are usually 25ºC average.

It is a really humid climatesince its precipitationsexceed 2,000 mm/year.

There is not any seasonalchange.

Tropical or savannahclimate.

Tropical or savannahclimate. It is locatedbetween the equatorand the tropics, so it isjust found in Africa, America and someparts of Australia. It isa hot climate that has a dry and a humidseason, so there are two kinds of tropical climates.

Wet tropical climate:its temperatures are quite high, although it is warmer during the humid season. They are never below 18ºC. It has a humid season with high precipitations. Total amount is between 500 and 2,000 mm/year.It has a short dry season when precipitations are almost nonexistent.

Dry tropical climate: this climate gets drier as it gets closer to the tropic. Its temperatures are really high. It has irregular rain during the summer. Thisclimate is a transition to thedesert climate.

Hot desert climate. It is usually located close to the tropics. It is a really hot climate during the day (c. 50ºC), but it cools during the night (c. 0ºC). However its average temperature is above 18oC. It is extremely dry, since it rains less than 250 mm/year. Whenit rains it falls as heavy downpours.

They are located between the tropics and the polar circles. All of them have four different seasons with changes in temperatures and precipitations.

Temperate climates.

Oceanic climate. It is usually a climate located on the west coasts of the continents at mid-latitude: Its temperatures are quite mild, since its average is between 10 and 15ºC. It has regular and abundant rain, more usual in winter. It exceeds1,000 mm/year.

Mediterranean climate. It is mostly located around the Mediterranean Sea, although it has some other locations in South Africa, California, Chile, and Australia: Its winter is quite mild, but its summer is hot and dry. Its averagetemperature is around15ºC. Precipitations are quite irregular and non-abundant (never over 800 mm/year). They are more common in spring and autumn.

Continental climate. It is aclimate with very littlemaritime influence since it isusually inland. It can only befound in the northernhemisphere (Europe, Asia,North America):Temperatures vary a lotbetween summers (hot) andwinters (really cold). Itsaverage temperature is around9ºC. Precipitations areirregular and they fall mostly insummer (circa 700 mm/year).Summer is really hot (almosttropical) and rainy.Precipitations are above 1,000mm/year, whereas the averagetemperature is between 15and 20oC.

Cold climates. They are located in high latitudes and altitudes.

Polar climate. It islocated above the polarcircles:There is not any warmsummer.Average temperaturesare around 0ºC andthey can reach up to -50oC.There are very fewprecipitations (less than300 mm/year), although.they remain frozen dueto the extremely lowtemperatures.

Alpine climate. It is located in the highest mountains of the world: Its temperatures are quite low, since their average does not

exceed 5ºC. It is a rainy climate with more than 1,500 mm/year.

ACTIVITIES:•Write down the names of the different climate zones of the picture:

Match each climate to its climate zone: •Mediterranean •Tropical•Alpine Hot•Polar Temperate •Equatorial Cold •ContinentalOceanic•Desert

• 18. Answer the following questions: – Which climates have the most precipitation?

– And which the least?

• 19. In what way is the equatorial climate different from the wet tropical climate? • 20. Answer the following questions:

– What are temperatures like in a polar climate?

– Is there much precipitation? Is it in form of rain or snow?

– What is the main difference between the Mediterranean climate and the humid sub-tropical climate?

• 21. Which climate type has the lowest temperatures?22. Are the following sentences true or false? Correct the wrong ones.

– An equatorial climate is always humid and hot.

– The polar and alpine climates have the lowest temperatures.

– The tropical climate is a kind of temperate climate.

– The oceanic climate is hot in summer and cold in winter.

• 24. Are the following statements true or false? Correct the wrong ones. – The atmosphere is the layer of gases that surrounds the Earth.

– Meteorological phenomena occur in the atmosphere.

– Climate is the same all over the planet.

– The temperate zone is located between 30o and 60o latitude north and south.

– The equatorial climate has very little precipitation