Weather and Climate Flashcards
What is weather?
the conditions of the atmosphere over a short period of time
What is climate?
how the atmosphere “behaves” over a long period of time - based off the pervious 30 years of weather
What are the different circulation cells?
Hadley Cell 0-30º
Ferrel Cell 30-60º
Polar Cell 60º-90º
Describe how air travels across the circulation cells
- at the equator, hot air rises to 15km, causing low pressure
- the air current divides, cools and moves 30º north and south, leading to high pressure
- some of the cooled air moves back to the equator as trade winds
- the rest travels towards the poles until it reaches 60º where the warmer air of the Ferrel cells meets the cold polar air
- the warmer air rises to form Polar cells, this air then travels to the poles where it cools and sinks, forming high pressure
What is the Coriolis Effect?
as the earth spins it rotates under the atmosphere
What is the Coriolis Effect?
as the earth spins it rotates under the atmosphere, forcing air to be deflected to the right in the northern hemisphere, and to the left in the southern hemisphere
How do ocean currents redistribute heat energy across the Earth?
- ocean currents transfer heat energy from areas of surplus (equator) to areas of deficit (poles)
- wind-driven surface currents and deeper ocean currents move warm water towards the poles and colder water towards the equator
- at the poles, water is cold and dense so sinks, and is replaced by warmer water from the equator - creating ocean currents e.g. the North Atlantic Drift/Gulf Stream
- cooler water flows back to the equator - forming cold currents e.g. the Humboldt Current
What is the troposphere?
part of the atmosphere which is 10-15km high where most of the weather takes place
What are the ways in which heat at the equator is redistributed around the world?
- oceanic circulation
- circulation cells
- the coriolis effect
What are the features of the Gulf Stream?
- Narrow - 50 miles wide
- 3mph
- 25ºC water
- splits into the north atlantic drift
What are the features of the North Atlantic Drift?
- widens to several hundred miles
- less than 1mph
- several sub currents
- splits into two at british isles and has considerable influence on the climate e.g. keeps Norwegian ports free of ice and UK is 5ºC warmer than other coteries on its latitude
Name a current that takes cold water back to the equator?
the Humboldt Current
What have been the main causes of climate change in the past?
- Milankovich cycles (orbital theory)
- solar variation (sun spot theory)
- volcanism (eruption theory)
(4. asteroid theory)
How have milankovich cycles caused climate change in the past?
- the way the earth orbits around the sun can change - leading to glacial periods of time (5-6ºC cooler) and interglacial (2-3ºC warmer)
- shape of the orbit may change - called eccentricity cycle - e.g. more circular (cooler) or more elliptical orbit (warmer) - every 100,000 years
- axial tilt cycle - greater tilt means more extreme temp changes between seasons - varies every 40,000 years
- “wobble” of the earth’s axis changes the direction the axis is facing - called a precession cycle every 24,000 years
How has solar variation caused climate change in the past?
- sunspots are black areas on the surface of the sun
- if sun has lots of spots it means the sun is more active than usual so more solar energy is given off
- sunspot cycles can cause climate change for a few hundred years
How has volcanism/asteroids caused climate change in the past?
- volcanic eruptions/asteroids produce ash and sulphur dioxide gas
- this spreads around the earth’s stratosphere by winds
- this causes a blanket of ash which will stop sunlight reaching the earth’s surface as the solar rays are reflected back into space - creating a glacial period for a few years/10 years
How does global warming occur?
- people burn fossil fuels which release greenhouse gases into the atmosphere
- solar rays are emitted from the sun and reach the earth through short wave energy
- heat energy is radiated back into space through long wave energy - however greenhouse gases clog the atmosphere and trap the heat energy within the earth’s atmosphere
What can be used to prove global warming?
- the keeling curve (amount of CO2 parts per million rising 310-400 over past 50 years)
- dendrochronology (wider gaps between rings on trees recently as more CO2 to photosynthesise and grow)
- ice cores (more bubbles means more CO2 in atmosphere)
- preserved pollen (provides evidence on warm and cold growing conditions)
What are the factors that are impacted by climate change?
- crop yields/food security
- water
- thermal expansion
- eustatic sea level rise
- extreme weather
- disease
What are the advantages of climate change on crop yields?
if UK temperature increases, farms will be able to grow more crop variety e.g. grapes
What are the disadvantages of climate change on crop yields?
global warming might impact the rate of photosynthesis, leading to lower crop yields, will impact food chains and lead to malnourished populations
What are the disadvantages of climate change on water?
some areas are more likely to flood e.g. Bangladesh (snow melts from Himalayas) and some areas are more likely to suffer from water stress e.g. the Sahel becoming more arid
What are the advantages of climate change on thermal expansion?
some fish like the increase in temperature
What are the disadvantages of climate change on thermal expansion?
flooding will occur as water is expected to expand as much as 4ºC by 2100
What are the advantages of climate change on the Eustatic Sea Level Rise?
Eustatic sea level rise leads to an increase in the volume of ocean biomes
What are the disadvantages of climate change on the Eustatic Sea Level Rise?
flooding occurs as sea levels rise - ice caps melting mean sea level will rise by 40cm by 2100
What are the advantages of climate change on disease?
more insects survive so thats good:)
What are the disadvantages of climate change on disease?
disease spreading insects survive which leads to more disease
What are the two periods of time that show climate change in the last 1000 years?
- the medieval warm period 950-1100
2. the little ice age 1600-1850
What were the features of the Medieval Warm Period?
- UK temp was much warmer and grapes could grow
- crop yields increased meaning more food was available
- occurred as a result of increase in sunspots
- 950-1100
What were the features of the Little Ice Age?
- UK temp dropped
- River Thames froze over
- crops failed and population declined
- due to volcanism and decrease in sunspots
- 1600-1850
What are tropical cyclones?
large rotating storms which form over oceans in tropical areas
How are tropical cyclones formed?
- high temperatures cause air to rise from the ocean surface
- the rising air causes thunderstorms
- sometimes these storms can group together and create a strong flow of rapidly rising warm air
- this makes an area of extreme low pressure at the centre of these storms
What are the conditions needed for a tropical cyclone to form?
- source of warm moist air (27ºC+)
- season when ocean water is warmest (june-november in north and november-april in south)
- winds converging the ocean surface
- formation a distance from the Equator so the coriolis effect can rotate the storm
What is the general movement of tropical cyclones?
do not remain where formed and will follow the direction of prevailing winds - when reaching land the hurricane is cut off from its energy source and there is less moisture so it slows
What is used to track tropical cyclones?
- satellite imagery
2. statistical modelling
Where do tropical cyclones form?
5º - 30º above and below equator - e.g. 15% of their activity happens in the Caribbean and the USA
What are the characteristics of a tropical cyclone?
- 5-6 miles high
- eye and eye wall
- spin anti-clockwise in northern hemisphere and clockwise in south (coriolis effect)
- moves at 10-40mph
- winds of 40mph + (if less then it is a tropical depression)
- 300-400 miles wide