Chapter 3: Weather and climate

• Aardrijkskunde
• Middelbare school
• havo, vwo
• Leerjaar 3

Chapter 3:
 

Weather and climate

Section 3.1.: Weather
Section 3.2.: Dutch climate

Section 3.3.: Climates in Europe

Section 3.4: The tropical climate

What is the difference between weather and climate?

Section 3.1. The weather

Learning goals:

1. Define the keyword weather 

2. Explain the four most important parameters when it comes to weather.

Weather is the current state of the atmosphere. It's measured on a time in a certain place.

 

Climate is the average weather over an extended period.

Longer period and larger area

We'll watch the BBC weather forecast of today. 

Which different elements of weather do you recognize? 

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Which different elements of weather did you recognize?

In the weather forecast you've recognised the four charecteristics or elements of weather:

• Temperature
• Precipitation
• Wind (speed and direction)
• Cloud cover 

With these four elements you can express the difference in weather between places.

Temperature

In the Netherlands measured in degrees Celsius using a thermometer.

Location influences the temperatures:

Further away from the equator the temperatures becomes less. 

The higher on a mountain the lower the temperature.

Isotherm temperature map of 

the USA 

Precipitation

There a two types of precipitation:

solid (e.g. hail and snow) 

and 

fluid (e.g. rain, fog).

Three important processes that make precipitation possible:

- Evaporation
- Transpiration

- Condensation

Precipitation always needs rising air!

Very important!

When air rises it gets colder, cold air can't hold as much water vapour then warm air so precipitation.

When air falls it gets warmer, so less precipitation

Very very important!

When air rises it gets colder, cold air can't hold as much water vapour then warm air so precipitation.

When air falls it gets warmer, so less precipitation

What is the difference between the small and large water cycle?

Wind

Wind is the movement of air through the atmosphere. 
In the forecast they mention wind speed (in Beaufort) and wind direction.
Wind always is named after the direction it came from, in the Netherlands that's mainly western wind.

Buys Ballot

Important law of Buys Ballot
1. Wind always moves from high pressure areas to low pressure areas;

2. Wind is deflected the right in the Northern Hemisphere and to left in the Southern.

Coriolis effect

Also wind goes the opposite direction in the Northern Hemisphere, but why?

That's because the Coriolis effect.

Air pressure

Is expressed in hectopascal hPa and on a map of the air pressure you see isobars.

Section 3.2. The Dutch climate

Learning goals:

1. Explain the difference between weather and climate 

2. Use a climate graph to describe the Dutch climate 

3. Draw a climate graph 

4. Explain why the earth has different seasons

What's the difference between weather and climate?

Why is the temperature near the tropics warmer then near the poles (figure 3.17)?

1. Distance from the sun is shorter near the equator;

2. The surface that is heated near the equator is smaller.

The climate of the Netherlands is influenced by it's location near the sea.

Seawater slowly warms up and slowly cools down compared to land surface. 
Therefore places near the sea have less differences in summer and winter temperatures.

Typically Dutch is also our annual rainfall. 

This rainfall is also caused by the location near the sea but also thanks to frontal rainfall.

The temperature of the Atlantic Ocean near Western Europe is higher than could be expected because it's location. 

That's because of the Gulf stream a warm sea current that originates from the Gulf of Mexico.

Section 3.3. Europe's climates

Learning goals:

1. Describe Köppen’s climate classification system.

2. Describe differences between climates in Europe.

3. Explain the effect of mountains on the climate 

4. Explain the different height belts in mountains. 

5. Determine using a climate graph which climate according Köppen’s classification system a place has 

The Netherlands has a maritime climate, but Europe has also different climates.

Köppens'climate classification

The German geographer Wladimir Köppen ordered all the climates in the world in his climate classification by investigating the vegetation in the world

Köppen uses letters for his climate classification. 

The first letter is always a capital, so:
A. tropical climates
B. Dry climates
C. Maritime climates

D. Continental climates

E. Cold climates

The second letter is a lower case letter with A, C en D.

f: no dry period

s: dry summer

w: dry winter

First determine which hemisphere a place is located

Dry (B) climates and cold (E) climates get a second capital letter:

BW (desert) and BS (steppe)

EH (high mountain range), ET (tundra) and EF (snow and ice on higher latitude).

What is the difference between BW and BS?

Annual rainfall:

BW: less then 200 mm rainfall per year
BS: more then 200 mm rainfall per year 

How do you determine the climate? 

Learn this scheme!
1. What is the temperature of the coldest month (can be January or July)?:
Warmer then 18 degrees = A

Between -3 degrees and 18 degrees = C

Colder then -3 degrees = D or E

2. For D or E
What is the temperature of the warmest month (January or July)?
Warmer then 10 degrees = D
Cooler then 10 degrees = E

3. for A, C or E
When is the dryest month?
Sommer: s

Winter: w

No dry month: f

If you compare temperatures on mountains you'll see that the temperature in the valley is always warmer then on the top.

Why?

The atmosphere is heated up by sun beams that are reflected by the earth's surface.

Every 1000 meters the temperature drops with 6 degrees.

Temperature also influences the vegetation (fig 3.30)

On a summer day I decide to walk up on a mountain. Temperature in the Valley is 18 degrees. What is the temperature on 1500 metres?

1. 18 degrees
2. 27 degrees
3. 9 degrees
4. 6 degrees

In the afternoon i've reached the top at 2000 metres. The temperature at the top is 3 degrees. What is the temperature in the valley ( 500 metres)?

1. -6 degrees
2. 3 degrees
3. 9 degrees
4. 12 degrees

Air that rises becomes

1. Colder
2. Warmer

Orographic rainfall

Air rises gets colder and precipitates. 
Decending air gets warmer so there is no precipitation.

3.4 Tropical climate 

Learning aims:

• Describe the two types of tropical climate
• Explain how the sun causes the wet and dry seasons in the savannah climate

A, tropical

Second letter

Look at the distribution of the precipitation throughout the year:

- No dry period ==> f
- Dry summer ==> s
- Dry winter ==> w

NOTE
The second letter in these climates is a normal letter, not a capital letter.

Am climate is a

1. Savannah climate
2. Monsoon climate
3. Dry climate

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What makes Bangkok Tropical?

The climate graph in Bangkok shows what type of climate?

Hadley cell circulation

Hadley cell

Tropical atmospheric circulation.

Trade winds

Prevailing winds in the tropics, blowing from east to west.

Intertropical convergence zone (ITCZ)
Area where the northern and southern trade winds come together, causing rising air and thunderstorms.

ITCZ

Hadley cell en de ITCZ

Stap 1

Hoge instraling zon bij de evenaar, hierdoor is er veel verdamping.

Deze warme vochtige lucht stijgt op. Op evenaar aan het aardoppelvlak ontstaat een lage drukgebied. 

Stap 2

Door de opstijging, koelt de warme vochtige lucht af. Het vocht condenceert waardoor er een wolk ontstaat. wanneer de wolk vol is, dan laat de wolk de druppels vallen, het regent.

Stap 3

De lucht die nu droog en koud is, daalt bij 30 graden noorderbreedte en zuiderbreedte weer richting het aardoppervlak. Hierdoor onstaat daar een hoge druk gebied. 

Stap 4

Je weet nu dat lucht altijd van hoge druk naar lage druk beweegd. Daardoor stroomt er nu een wind van 30 graden noorderbreedte en zuiderbreedte richting de evenaar, dit noem je ook wel de passaat. Op het Noorderlijkhalfrond heet hij de Noordoost passaat. Bij de evenaar komen de passaat winden samen, dit wordt ook wel convergeren genoemd,  noemen ze ook wel de Intertropische convergentie zone (ITCZ)

Stap 3

De lucht die nu droog en koud is, daalt bij 30 graden noorderbreedte en zuiderbreedte weer richting het aardoppervlak. Hierdoor onstaat daar een hoge druk gebied.

Stap 4

Je weet dat lucht altijd van hoge druk naar lage druk beweegd. Daardoor stroomt er nu een wind van 30 graden noorderbreedte en zuiderbreedte richting de evenaar, dit noem je ook wel de passaat. Op het Zuiderlijkhalfrond heet hij de Zuidoost passaat. Bij de evenaar komen de passaat winden samen, dit wordt ook wel convergeren genoemd, noemen ze ook wel de Intertropische convergentie zone (ITCZ)

ITCZ

ITCZ is...