Podcast
Questions and Answers
Atmospheric pressure is measured in cm or pounds.
Atmospheric pressure is measured in cm or pounds.
False
Isobars on a weather chart represent areas of equal atmospheric pressure.
Isobars on a weather chart represent areas of equal atmospheric pressure.
True
High pressure is defined as atmospheric pressure at 74 cm or higher.
High pressure is defined as atmospheric pressure at 74 cm or higher.
False
When isobars are drawn close together, it indicates calm weather.
When isobars are drawn close together, it indicates calm weather.
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An increase in altitude results in an increase in atmospheric pressure.
An increase in altitude results in an increase in atmospheric pressure.
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Moist air is lighter than dry air due to the presence of water vapour.
Moist air is lighter than dry air due to the presence of water vapour.
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Winds are caused by the movement of air from high pressure to low pressure areas.
Winds are caused by the movement of air from high pressure to low pressure areas.
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A higher temperature results in higher atmospheric pressure.
A higher temperature results in higher atmospheric pressure.
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High pressure is associated with cloudy skies.
High pressure is associated with cloudy skies.
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The Coriolis Effect causes winds in the northern hemisphere to be deflected to the south.
The Coriolis Effect causes winds in the northern hemisphere to be deflected to the south.
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The Trade Winds blow from the east to the west.
The Trade Winds blow from the east to the west.
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The Polar High Pressure Belt is created due to high temperatures throughout the year.
The Polar High Pressure Belt is created due to high temperatures throughout the year.
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Land breezes occur during the day and blow from the land to the sea.
Land breezes occur during the day and blow from the land to the sea.
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Westerlies are characterized by being regular and constant in strength and direction.
Westerlies are characterized by being regular and constant in strength and direction.
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The Sub-Polar Low Pressure Belt is created due to the convergence of cold and warm air.
The Sub-Polar Low Pressure Belt is created due to the convergence of cold and warm air.
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Sea breezes occur during the night and blow from the land to the sea.
Sea breezes occur during the night and blow from the land to the sea.
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The Doldrums is another name for the Sub-Tropical High-Pressure Belt.
The Doldrums is another name for the Sub-Tropical High-Pressure Belt.
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The South West Monsoon Winds bring rainfall to the Asian land masses from the Indian Ocean.
The South West Monsoon Winds bring rainfall to the Asian land masses from the Indian Ocean.
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Cyclonic conditions arise from the convergence of similarly tempered air.
Cyclonic conditions arise from the convergence of similarly tempered air.
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Trade winds have the same effect on all continents they encounter.
Trade winds have the same effect on all continents they encounter.
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The winds called 'Roaring Forties' refer to westerlies blowing strongly in the Southern Hemisphere.
The winds called 'Roaring Forties' refer to westerlies blowing strongly in the Southern Hemisphere.
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The equatorial region experiences low pressure due to cold air sinking.
The equatorial region experiences low pressure due to cold air sinking.
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Study Notes
Atmospheric Pressure
- Atmospheric pressure is the pressure exerted by the weight of air above a point on Earth's surface.
- Measured using a barometer.
- Units include centimeters of mercury (cm) and millibars (mb).
- High pressure is 76 cm or above (1013 mb).
- Low pressure is 74 cm or below (986 mb).
- Pressure is shown on weather charts by isobars.
- Isobars are lines connecting areas of equal atmospheric pressure.
- Close isobars indicate significant pressure differences and stormy weather.
- Far isobars indicate little pressure difference and calm weather.
Factors Affecting Atmospheric Pressure
- Temperature: Higher temperature leads to lower pressure (warm air rises). Lower temperature leads to higher pressure (cold air sinks).
- Altitude: Higher altitude means lower pressure. Air density decreases with altitude.
- Water Vapor: Moist air (containing water vapor) is lighter and rises, creating low pressure. Dry air (containing heavier gases like nitrogen and oxygen) sinks, creating high pressure.
Winds
- Wind Formation: Winds are caused by air moving from high-pressure areas to low-pressure areas.
- Weather Influence: High temperature creates low pressure, rising air, clouds, and hence cloudy skies. Low temperature creates high pressure, sinking air, and clear skies.
- Coriolis Effect: Deflects winds to the right in the Northern Hemisphere and to the left in the Southern Hemisphere.
Pressure Belts
- Equatorial Low-Pressure Belt: High temperatures lead to rising warm air, creating a low-pressure area near the equator.
- Subtropical High-Pressure Belt: Cool, sinking air from the equatorial region, coupled with deflection by Earth's rotation, creates a high-pressure zone at the subtropics.
- Subpolar Low-Pressure Belt: Air is deflected by Earth's rotation to the subtropical regions, causing a low-pressure area at the subpolar region.
- Polar High-Pressure Belt: Low temperatures and sinking cold air create a high-pressure belt at the poles.
Permanent Winds
- Trade Winds: Easterly winds blowing from the subtropical high-pressure belts to the equatorial low-pressure belts. NE trades in the Northern Hemisphere; SE trades in the Southern Hemisphere.
- Westerlies: Westerly winds blowing from the subtropical high-pressure belts to the subpolar low-pressure belts. SW westerlies in the Northern Hemisphere; NW westerlies in the Southern Hemisphere. Stronger in the Southern Hemisphere due to wider open spaces.
- Polar Easterlies: Easterly winds blowing from the polar high-pressure belts to the subpolar low-pressure belts; NE polar easterlies in the Northern Hemisphere; SE polar easterlies in the Southern Hemisphere.
Periodic Winds
- Land and Sea Breezes: Local winds that occur due to differential heating of land and water. Land breeze blows from land to sea at night; sea breeze blows from sea to land during the day.
- Monsoon Winds: Seasonal winds, primarily in South Asia. Southwest monsoon in summer (ocean to land), driven by differential heating; northeast monsoon in winter (land to ocean).
Rainfall Patterns
- Trade Winds: Bring rainfall to the eastern sides of continents.
- Westerlies: Bring rainfall to the western sides of continents.
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Description
This quiz covers the fundamentals of atmospheric pressure, including how it is measured, its impact on weather, and factors that influence it, such as temperature, altitude, and water vapor. Test your understanding of isobars and their significance in meteorology.
