Questions and Answers
What happens to atmospheric pressure as altitude increases?
Pressure decreases with increasing altitude.
Explain how atmospheric pressure is related to air density and air temperature.
There is more pressure when gas is denser.
What causes a thermal high near the surface? A thermal low?
Thermal highs come from cold surface temperatures and thermal lows from warm surface temperatures.
What causes a dynamic high near the surface? A dynamic low?
Signup and view all the answers
Define the following terms: barometer, millibar, isobar.
Signup and view all the answers
What is meant by a pressure gradient?
Signup and view all the answers
What three factors influence the direction of wind?
Signup and view all the answers
How and why are friction layer (surface) winds different from upper-atmosphere geostrophic winds?
Signup and view all the answers
Describe the relationship between the 'steepness' of a pressure gradient and the speed of the wind.
Signup and view all the answers
What is a cyclone?
Signup and view all the answers
What is an anticyclone?
Signup and view all the answers
What are Hadley Cells?
Signup and view all the answers
Describe global wind patterns.
Signup and view all the answers
What are the Polar Easterlies?
Signup and view all the answers
What are the Prevailing Westerlies?
Signup and view all the answers
What are the Horse Latitudes?
Signup and view all the answers
What are the Trade Winds?
Signup and view all the answers
Study Notes
Atmospheric Pressure and Wind
- Atmospheric pressure decreases with increasing altitude, as there are fewer air molecules above a surface at higher elevations.
- Greater air density results in higher atmospheric pressure, with more molecule movement generating heat (higher temperatures).
Thermal and Dynamic Pressure Systems
- Thermal highs are caused by cold surface temperatures, while thermal lows result from warm surface temperatures.
- Dynamic highs occur with strongly descending air, whereas dynamic lows form through strongly rising air.
Pressure Measurement and Definitions
- A barometer is an instrument for measuring atmospheric pressure.
- Millibar is a unit expressing force per surface area, while isobars are lines connecting areas of equal pressure.
Pressure Features
- A "high" refers to higher pressure relative to surrounding areas, while a "low" indicates lower pressure.
- A ridge represents an elongated area of high pressure; a trough denotes an elongated low pressure area.
Wind Dynamics
- The pressure gradient measures the horizontal rate of pressure change, influencing wind direction.
- Wind is affected by the Coriolis effect, pressure gradients, and surface friction.
- Friction layer winds interface with the earth's surface, whereas upper-atmosphere geostrophic winds flow parallel to isobars unaffected by surface friction.
Pressure Gradient and Wind Speed
- A steeper pressure gradient leads to higher wind speeds due to rapid air acceleration, while a gentle gradient results in slower winds.
Cyclones and Anticyclones
- Cyclones are systems where winds rotate inward to a low-pressure area, with counterclockwise circulation in the northern hemisphere and clockwise in the southern hemisphere.
- Anticyclones feature high-pressure centers, with air circulating slowly and associated with calm and pleasant weather.
Hadley Cells
- Hadley Cells are large-scale convection systems where air rises at the equator and sinks at about 30° latitude north or south.
Global Wind Patterns
- Winds are named for their originating direction and there are six major wind belts: polar easterlies, westerlies, and trade winds in each hemisphere.
- These belts shift north in summer and south in winter, each covering about 30 degrees of latitude.
Specific Wind Belts
- Polar Easterlies: Blow irregularly from the east and north at 60-90 degrees latitude; the polar front distinguishes them from westerlies.
- Prevailing Westerlies: Found at 30-60 degrees latitude, blowing from the west and moving weather patterns across the U.S. from west to east.
- Horse Latitudes: Occur at about 30 degrees, where westerlies and trade winds meet, characterized by high pressure, dry air, and variable winds.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
Explore essential concepts about atmospheric pressure and its relationship with altitude. This quiz focuses on key definitions and explanations that clarify how changes in altitude affect air pressure. Perfect for students looking to deepen their understanding of meteorological principles.