Weather and Climate Flashcards
What is climate?
it is the condition of the average weather as observed over a long period of time, eg 30 years , and over a large area.
includes:
- pressure
- temperature
- wind
- humidity
- precipitation.
What is weather?
- it is the atmospheric conditions as observed over a short period of time in a local area.
- Includes theres conditions:
- temperature
- humidity
- precipitation
- wind
- sunshine
Describe a stevenson screen.
- it is made of wood.
- placed with its door to the south.
- Stands 120 centimeters from the ground.
- double roof for insulation.
- painted white.
- has slats on the side to allow gentle flow of air.
- placed away from building or trees.
- contains:
- barograph
- barometer
- wet and dry bulb thermometer
- maximum and minimum thermometers.
Describe the minimum and maximum thermometer.
- shows the highest and lowest temp.
- tube shaped like a U.
- one side has a bulb containing alcohol.
- the other has a vacuum.
- mercury is at the bent of the U.
- the mercury is pushed around by the alcohol during expansion or contraction,
- the mercury indicates the current temperature as observed.
- there are a small metal index in each arm.
- they are pushed by the mercury.
- the metal indixes indicates the maximum and minimum temp for the day.
- they have to be resetted by a magnet.
NB- indexes should be read from their bottom.
Describe a Hygrometer ( W and D thermometer )
- Two identical thermometers.
- one of the bulbs covered in a wick that hangs into a container of distilled water.
- the water rises up the wick and evapourates.
- evapouration causes cooling of the bulb.
- the drier the air, the more evaporation will occur.
- the bigger the difference between wet and dry bulbs, the drier the is shall be.
- the difference and a graph is used to calculate the humidity.
What is a barometer?
- it is a device used to measure atmospheric pressure.
- it contains a small drum with a vacuum inside.
- the air pressure exerts a force on this drum
- the changes in atmospheric pressures causes the box to contract or expand.
- they pointers moves as it happens.
What is a Barograph?
- it is a barometer that also has a vacuum drum, but it is attched to a pen which draws a line on a piece of paper that slowly rotates.
- thus you can have a continuous record of air pressure.
What is a anemometer?
- it measures the wind speed.
- it has cups that are connected to arms.
- as the wind blows it turns these cups and arms.
- a counted desplay the wind speed in knots.
- ## must be erected in a open area.
What is a wind vane?
- measures the wind direction.
- wind is always measure in the direction it comes from.
What is a rain gauge?
- it measures rainfall in mm
- made from non corrosive material.
- place away from structures.
Name and explain the types of isolines.
- isotherms: connects the places with the same temp.
- isobars: connects places with the same atmospheric pressure.
- isoyets: connect places with the same rainfall.
How do you record the average temp of the day?
Maximum+ minimum devide by 2
Know the Station model on page 10.
What i said above.
Name the Precipitation symbols ( in notes pg 11 )
LEES DAAR BO!!!!!
Name and identify the frontal symbols ( in notas pg 11 )
Ek raak moeg vir dit. die werk is darem beter as natural vergetations.
Name the long term factors that influence temp.
- height above sea level.
- angle of the sun
- presence of water.
- ocean currents
- prevailing winds.
Explain how the height above sea level influences the temp.
- atmosphere is heated by:
- short-wave radiation from the sun that heats the earth which then releases long wave radiation.
- thus the further from the source of heating, the cooler.
- temeratures drop 1 degree for every 100m up.
- air pressure also decreases as you move and thus less heat retained.
Explain how the angle of the sun infuence the temp on the long term.
- when the sun is vertically overhead, the rays strike earth at a verticlle angle.
- less likely to scatter due to reflection.
- all heat concentraded on small area.
- the greater the angle of the rays, the less concentrated the energy.
- rays also travels longer distances through space before reaching the earth.
How is the presence of water a long term influence on temp?
- Water allows rays to penetrate deeper.
- thus more heat is dispersed.
- movement of water also disperses heat.
- water also reflects light.
- water heats up slower that land.
- retains heat longer that land.
How do ocean currents influence temp as a long term factor.
- warm ocean current move towards polar regions.
- they raise the temp in the area in which they flow.
- cold currents take cold water to equator.
- they lower the temp where they go.
how do prevailing wind play as a long term factor that influences temp?
- wind take the temp of the area over which they blow.
- therefore cold wind can decrease temp and decrease rainfall.
- thus this is why namibia is a desert.
Name the Short term factors of temperature.
- influence of the seasons.
- local influences like:
- aspect of slope
- land use
- cloud cover
- urban heat islands
- temperature inversion.
How does the seasons contribute to the short term influence on temp?
- during the southern hemisphere’s summer, the earth is tilted away from the sun.
- thus the south is closer to the sun and the tremp increases.
- the days are also longer that the night.
- during winter, the earth is tilted towards the sun
- the south is further from the sun, thus the temperature will be colder.
Name two local influences of temp and explain why they are.
- Aspect of slope.
- in the SH a north- facing slope recieves the greatest amount of sunlight.
- they are thus warmer that the south- facing. - land use:
- land, cleared of vegetation, heat up more.
- building material like cement absorbs more heat.
- built up areas will heat up more that plants.
Why do cloud cover contribute to the short term influences of temp?
- the more clouds, the more heat is reflected.
- the earth will recieve less heat and thus absorb less.
- clouds also acts as a insulation.
- thus raising temp.
Why are urban heat islands classified as a short term influence of heat?
- the temp is usually higher because:
- building materials absorb more heat than plants.
- cities produce artificial heat.
- pollution absorbs heat.
- tall buildings recieve sunlight for much longer.
study pages 18-21 in packet.
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