Variable Weather & Changing Climate KQ1 - Why Do Different Places Experience Different Weather and Climate?

What is the difference?

Weather refers to the condition of the atmosphere at a particular place and time.

Climate is the average condition of the atmosphere of a specific place over a long period of time, usually over 30 years.

We can describe weather with the six following elements

1. Temperature - degree of hotness or coldness of a place
2. Relative Humidity - amount of water vapour the air can hold at a given temperature
3. Clouds - visible masses of water droplets or ice crystals which are suspended in the atmosphere
4. Rainfall - precipitation or water that falls from the atmosphere down to the surface of the earth
5. Air Pressure - force exerted on an unit area of earth's surface by a column of air
6. Wind - movement of air from an area of high to low pressure

Temperature is determined by the amount of energy from the sun which reaches the earth. Most of the sun's energy travels through the atmosphere and is absorbed by the earth's surface, causing it warm up and heats up the atmosphere (Refer to the diagram below)

Temperature is regularly measured and recorded it is measured in degrees Celsius (°C) or degree Fahrenheit (°F). It is measured using a thermometer. Usually, we usually record temperatures because it allows us to determine weather patterns of a place. 

We can do this by calculating the

• Mean Daily Temperature - Sum of hourly temperatures divided by 24 hours
• Mean Monthly Temperature - Average daily temperatures recorded in a month
• Mean Annual Temperature - Average temperature recorded in a year
• Temperature Range - Difference between maximum and minimum temperature
• Diurnal Temperature Range - Difference between maximum and minimum temperatures in a day
• Annual Temperature Range - Difference between maximum and minimum mean monthly temperatures recorded in a year

In the study of weather, anything above 20°C is considered high temperature and low temperature as below 10°C.

Why Different Places Experience Different Temperatures?

Temperatures vary across the earth. Some places are colder while others are warmer.

Factors that cause variations include

• Latitude - distance of any point of on earth measured north or south from the Equator
• Altitude - height of a place in relation to the sea level
• Distance from the Sea - how near or far a place is from the sea which results in a difference between the rate of heating and cooling
• Cloud Cover - extent of the sky covered by clouds

*I have covered the first two factors in the previous posts, click on it to redirect the page to the post :)

Distance from the Sea

Places near the sea experience smaller annual temperature range due to the Maritime Effect - It is the effect that large ocean bodies have on the climate of coastal areas. The sea heats up and cools down slower than land, causing it to have a smaller annual temperature range. 

During summer, the air over the sea is cooler than the air over the land. The cooler air over the sea helps lower the temperatures of coastal areas, therefore making the climate of the coastal places cooler than areas further inland.

Coastal areas experience cooler summers and warmer winters as a result of the maritime effect. 

Continental Effect on the other hand, refers to the effect that continental surfaces have on the climate of inland areas, Land heats up and cools down quicker than the sea. Therefore resulting in larger annual temperature range, and inland areas experiencing warmer summers and cooler winters 

Cloud Cover

The amount of cloud cover influences the temperatures on the earth's surface in the day and night. More cloud cover will result in a smaller difference between day and night temperatures, while less cloud cover will result in a larger difference between day and night temperatures - diurnal range. 

In the day, cloud cover also reduces the amount of direct sunlight an area receives, resulting in cooling. While at night, it traps longwave radiation radiated from the earth's surface which results in warming. 

Living with Tectonic Hazards KQ3 - How Do People Prepare For and Respond to Earthquakes?

Preparedness Measures 

Even though people are not able to prevent earthquakes and other tectonic hazards from happening, they can implement measures to prepare themselves to cope with the impacts of the earthquakes. This reduces the extent of damage and allow populations to survive an earthquake.



Some of this preparedness measures include (B.E.L.T)

• Building and Infrastructure Development - building and reinforcing infrastructures that are resistant and able to withstand potential earthquakes (e.g. Taipei 101, Taiwan)
• Emergency Drills - getting people to be familiar with procedures in the event of an earthquake
• Land Use Regulations - implementing rules and guidelines to restrict developments in earthquake prone areas
• Technology - monitoring and warning systems to warn populations

Although these preparedness measures may prepare people and help them mitigate the impacts of the earthquakes, there may be limitations (M.A.C) to reduce the effectiveness of these measures. Some of which includes

• Manpower - to construct and/or reinforce building to become earthquake-resistant, it requires specialists such as engineers. In addition, the enforcement of rules and regulations will require more law enforcement officers (i.e. government agencies, police etc)
• Adherence to Rules and Regulations -  uncooperative individuals or companies may not follow the rules and regulations implemented by the government. People may also not treat the emergency preparedness drills seriously and follow the procedures set.
• Costs - construction and maintenance of buildings and infrastructure that are earthquake-resistant may be expensive. Some areas may also be privately owned, therefore governments may have to purchase and acquire land to compensate these owners in order to move them out. Acquiring and building of advanced monitoring technology may be too expensive especially for lower-developed countries

In the event of an earthquake, there will be two levels of responses  by the people

1. Short-term (i.e. responses that occur immediately after the event and last for weeks) - search and rescue survivors, providing them with basic necessities such as food, shelter and water.
2. Long-term (i.e. responses that stretch over months and years) - rebuilding the region and preparing for future earthquake events to reduce extent of damage (i.e. preparedness measures)

Living with Tectonic Hazards KQ2 - Phenomena Found At Plate Boundaries and How They Are Formed

Phenomena which are associated with plate movements include earthquakes, tsunamis and volcanic eruptions.

Earthquakes

Picture showing a magnitude 6.4 earthquake that shook Taiwan

An earthquake is a vibration in the earth's crust caused by the sudden release of stored energy in the rocks found along fault lines. They occur when there is plate movement along plate boundaries, which cause the slow-build up of stress on the rocks found on either side of the fault.

• When the rocks can no longer withstand the increasing stress, they suddenly slip and release energy in the form of seismic waves which radiate from a focal point (i.e. focus). 
• The amount of energy released is measured using the Richter Scale and described as the magnitude of an earthquake.
• The point on the earth's surface directly above the focus is also known as the epicentre. 

After an earthquake event, the stress from the ground may cause many smaller earthquakes called aftershocks to occur along the fault lines. These series of aftershocks may occur for several months after the initial earthquake, with some of them being nearly as powerful as the original earthquake.

Recent example of major earthquake events include the 9.0 magnitude in 2011 - Tohoku, Japan, with a death toll of 28,000 people.

The extent of damage caused by an earthquake may vary based on population density of an area, level of preparedness, distance from the epicentre, time of occurrence and type of soil,

Test Your Knowledge: What are some countries that frequently experience earthquake events? Why?

Tsunamis 

Some of the hazards commonly associated with an earthquake is a tsunami. Tsunami refers to an unusually large sea wave which may be formed by

• Movement of sea floor during a large earthquake at the subduction zones
• Underwater landslide
• Landslide above sea level due to earthquakes or volcanic eruptions which causes large amount of materials to plunge into water

This causes loss of lives, disruption of services, fires, landslides, destruction of properties and properties (e.g. tsunami in Banda Aceh, Indonesia caused by earthquake in the Indian Ocean). 

Watch the video below to get a better understanding on how tsunamis are formed and its threats.

Volcanic Eruptions

Volcanic eruptions can occur on land or on the sea floor. They occur depending on whether a volcano is active, dormant or extinct.

• Active - a volcano that is currently erupting or expected to erupt in the future
• Dormant - a volcano that is currently inactive but may erupt in the near future
• Extinct - a volcano without current seismic activity and has no evidence of eruptions for the past thousand years. 

Some of the risks of living near volcanic areas include

• Destruction of properties and infrastructure caused by volcanic materials (i.e. lava, pyroclasts, lahar)
• Disruption of services (i.e. aircrafts and flight services)
• Landslides due to structural collapse of a volcanic cone
• Environmental pollution from ash particles ejected during the volcanic eruption
• Effects on weather due to release of gases such sulphur dioxide reflect sun's energy back into space and temporarily cools the earth ranging from a few months to years. 

Why Do People Still Live Near Volcanic Areas Since There Are Risks?

Although there are many risks in living near volcanic areas,  many people continue to live there due to its numerous benefits and opportunities. These includes

• Fertile volcanic soil for agriculture due to the breaking down (weathering) of volcanic materials to enrich the soil, making it favourable for agriculture
• Precious stones and minerals which can be used for commercial or building and construction purposes
• Tourism
• Geothermal energy

People may choose to continue living in areas prone to tectonic activity for a variety of reasons, considering the risks and opportunities. They cannot prevent natural hazards but live in harmony with nature through mitigation and preparedness measures which will be discussed in the next post.