WEATHER Flashcards
(25 cards)
Define weather
The condition of the atmosphere at a particular place and time
Define climate.
The average condition of the atmosphere at a specific place over a long period of time, usually over 30 years
Define temperature.
It is the degree of hotness and coldness of a place
What is the range for low, moderate, and high temperature respectively?
Low temperature: Below 10°C
Moderate temperature: In between 10°C and 20°C
High temperature: Above 20°C
What is the range for low, moderate, and high temperature range respectively?
Low temperature range: 10°C
Moderate temperature range: In between 10°C to 15°C
High temperature range: Above 15°C
How do you measure the minimum and maximum temperature?
Using a Six’s thermometer
How does latitude affect temperature?
Higher latitude, solar angle (angle at which Sun’s ray reach the earth) is smaller so solar energy is spread over a larger area. Therefore, lower temperature and vice versa.
In conclusion: Latitude is inversely proportional to temperature
Higher latitude –> solar angle smaller –> solar energy spread over wider area –> lower temperature
Smaller latitude –> solar angle larger –> solar energy concentrated over smaller area –> higher temperature
What are the 4 factors that affect temperature?
1) Latitude
2) Altitude
3) Distance from the sea
4) Cloud cover
How is the earth atmosphere heated up?
The earth’s surface absorbs about 45% of shortwave radiation directly. The warm surface then emits heat in the form of longwave radiation which is absorbed by greenhouse gases such as carbon dioxide in the atmosphere. When the atmosphere absorbs longwave radiation, solar energy is trapped and this warms the earth.
How much does temperature decrease by for every 1000m increase in altitude?
temperature decreases by 6.5°C
Why does temperature decrease when altitude increases?
This is mainly due to 2 factors:
1) As altitude increases, distance from the earth’s surface increases so this makes the air at higher altitudes to absorb lesser heat from longwave radiation emitted by the Earth’s surface.
2) At higher altitudes, air is less dense. Less dense air absorbs less heat from longwave radiation.
How is the temperature of coastal areas affected by the maritime effect?(effect of the ocean’s airflow on the climate of the surrounding areas)
Coastal areas experience cooler summers. This is due to:
1) Land heats up quicker than the sea so warmer land, cooler sea.
2) Cooler air over the sea lowers the temperature of the coastal areas.
3) Therefore, there is cooler summer.
Coastal areas experience warmer winters. This is due to:
1) Sea cools more slowly than land so warmer sea, cooler land.
2) Warmer air over the sea increases the temperature of the coastal areas.
3) Therefore, there is warmer winter.
Due to the effect of cooler summer and warmer winter, there is a smaller annual temperature range for coastal areas than inland areas.
How does the continental effect affect the temperature of inland areas?
Inland areas experience warmer summers. This is due to:
1) Land heats up more quickly as inland areas are not influenced by the sea so warmer land
2) Therefore, warmer summer.
Inland areas experience cooler winters. This is due to:
1) Land loses heat more quickly as inland areas are not influenced by the sea so cooler land.
2) Therefore, cooler winter.
Due to warmer summer and cooler winter, inland areas have a larger annual temperature range than coastal areas.
How does presence of cloud affect temperature?
It affects temperature differently during the day and during the night. During the day:
1) Clouds reflect a large portion of the sun’s energy back into space
2) Clouds also absorb heat radiated from the Earth’s surface
3) As a result, the Earth’s surface is cool and the air near the Earth’s surface is warm
During the night:
1) Clouds absorb heat that is radiated from the Earth’s surface and prevents it from escaping into space
2) As a result, the air near the Earth’s surface is warm
Therefore, there is a smaller diurnal temperature range.
How does absence of cloud affect temperature?
It affects temperature in two ways during the day and night. During the day:
1) Absence of clouds allows large amounts of the sun’s energy to reach the Earth.
2) The Earth’s surface heats up quickly so the air near the Earth’s surface is warm.
During the night:
1) Absence of clouds allows more of the heat radiated from the Earth’s surface to escape into space.
2) The air near the Earth’s surface is cool.
Therefore, the absence of clouds results in a larger diurnal temperature range.
Define relative humidity
It is the ratio between the actual amount of water vapour present in a mass of air and the maximum amount of water vapour the air could hold at a given temperature.
What is the formula for calculating relative humidity?
Relative humidity = Actual amount of water vapour in the air/maximum amount of water vapour the air can hold *100%
Why is temperature and relative humidity inversely proportional?
As temperature increases, the air expands and has a greater capacity to hold more water vapour. Hence, when the amount of water vapour in the air stays the same, the relative humidity decreases.
Define saturation.
Saturation is when the air holds the maximum amount of water vapour it can hold.
What is dew point temperature and what happens during dew point temperature?
Dew point temperature is the temperature at which saturation occurs. At dew point temperature, condensation occurs where water vapour changes to water by cooling.
How are clouds formed?
1) Earth surface is heated up and water evaporates to water vapour
2) Water vapour rises into the air and as it rises, it starts to cool.
3) When water vapour is cooled till dew point temperature, condensation occurs if there are condensation nuclei (non-gaseous particle for the water vapour to cool on) to allow the gaseous water vapour to condense into water droplets.
4) The water droplets in the air will merge and become larger forming clouds.
What is the range for low, moderate, and high rainfall respectively?
Low rainfall: Below 250mm
Moderate rainfall: In between 250 and 1500mm
High rainfall: Above 1500mm
What are the two types of rainfall?
1) Conventional Rainfall
2) Relief Rain
How is conventional rain formed?
1) The sun’s energy reaches the Earth.
2) The earth’s surface is heated up by the sun’s energy. This in turns heats up the surrounding air.
3) Water vapour is heated up, expands and rises.
4) As the water rises, it cools down. When it cools down and reaches the dew point temperature, condensation occurs.
5) Cumulonimbus clouds are often formed
6) When water droplets become large and heavy enough, they fall to the ground as conventional rain.
