Exam 3 FC2

What direction does the Coriolis effect deflect moving air in the Northern Hemisphere?

To the right

What are the three main forces acting on moving air?

Coriolis, Friction, Pressure Gradient Force

What is the boundary layer?

The layer affected by surface friction

How high above the surface does the boundary layer extend?

1-2 km

What effect does surface friction have on wind?

Slows it down

In the Northern Hemisphere, which direction does wind rotate around a high pressure center?

Clockwise

What is geostrophic wind?

Wind resulting from the balance between PGF and Coriolis

On an upper-air chart, what does a ridge indicate?

High pressure and sinking air

What type of wind is typically associated with warm air rising from a valley during the day?

Valley breeze

What is a characteristic of the Santa Ana wind?

Dry and warm

In the Southern Hemisphere, high pressure systems rotate in which direction?

Counterclockwise

What causes a geostrophic wind to occur aloft?

Balance between pressure gradient force and Coriolis

Which type of current is typically found on the eastern side of an ocean basin?

Cold current

Which of the following is a Western Boundary Current?

Gulf Stream

What happens to Coriolis force as surface wind speed decreases due to friction?

It becomes less important

What type of wind flows from warm land to cooler ocean at night?

Land breeze

What does convergence aloft typically cause at the surface?

Sinking air and high pressure

What term describes a dry, warm wind that blows down the leeward side of a mountain?

Foehn wind

Which local wind is often referred to as the “snow eater”?

Chinook

Which local wind can create extreme fire conditions in Southern California?

Santa Ana wind

What force is responsible for initiating air movement from high to low pressure?

Pressure Gradient Force

What does isobar spacing on a weather map indicate?

Wind speed and pressure gradient

What happens when isobars are close together?

Strong pressure gradient and high winds

In which situation does friction play the most significant role in wind direction?

Near the surface

Which way does surface wind cross isobars around low pressure in the Northern Hemisphere?

At a 45° angle inward

What is the typical wind direction around a surface low pressure system in the Northern Hemisphere?

Counterclockwise and inward

What is the general vertical motion of air in a surface low pressure system?

Rising

What force acts opposite the direction of wind and slows it down near the surface?

Friction

What is wind called that blows parallel to straight isobars above the friction layer?

Geostrophic wind

What does the term 'gradient wind' refer to?

Wind that balances PGF and Coriolis on curved isobars

What type of circulation is associated with a surface high pressure system?

Anticyclonic

Which direction do surface winds blow around a high pressure system in the Southern Hemisphere?

Clockwise and outward

What type of wind occurs when cool air flows downslope at night?

Mountain breeze

What time of day does a valley breeze typically develop?

During the day

Which wind system helps transport warm water toward western coasts of continents?

Western boundary currents

Why do sea breezes occur during the day?

Land heats faster than ocean

What causes air to spiral inward toward a low pressure center?

Friction and Coriolis force

Where do Santa Ana winds originate?

Mojave Desert

What characteristic defines katabatic winds?

Cold, dense air descending rapidly

What kind of pressure system is associated with subsiding (sinking) air?

High pressure

What type of wind flows from areas of higher pressure to areas of lower pressure?

All winds

What is a jet stream?

A fast, narrow air current in the upper troposphere

Which type of wind is most influenced by the pressure gradient force and Coriolis effect, but not by friction?

Geostrophic wind

What is the name of the wind that typically brings dry, warm air to the west side of the Rockies?

Chinook wind

What causes a monsoon?

Differential heating of land and sea

What causes wind direction to curve instead of moving in a straight line?

Coriolis effect

Which direction does the Coriolis effect deflect winds in the Southern Hemisphere?

To the left

What is the result of surface divergence in a high pressure system?

Sinking air and fair weather

What type of breeze blows from sea to land during the day?

Sea breeze

What is the approximate height of the jet stream?

10–15 km

Which wind pattern is associated with high-pressure systems aloft?

Diverging wind

What best describes the movement of air in a cyclone?

Inward and counterclockwise (Northern Hemisphere)

What is responsible for the rotation of cyclones and anticyclones?

Coriolis effect

What happens when there is convergence at the surface?

Rising motion and potential cloud formation

What local wind is strongest during clear nights in mountainous regions?

Mountain breeze

What causes valley breezes to form?

Daytime heating of slopes

What is the direction of airflow around a low pressure center in the Southern Hemisphere?

Clockwise and inward

Why is surface wind not purely geostrophic?

Due to frictional effects

What term refers to air flowing out from a high pressure system?

Divergence

When air rises in a low pressure area, what typically follows?

Cloud formation and precipitation

What is the main reason surface winds cross isobars instead of flowing parallel?

Friction reduces Coriolis deflection

Which wind system helps balance global heat differences between the equator and poles?

Global circulation

What happens to rising air in a low pressure system?

It expands and cools

What is the source region for Santa Ana winds?

Desert interior

What is the main driver of all wind on Earth?

Solar heating

What type of air movement is associated with surface convergence?

Rising motion

What direction do anticyclones rotate in the Northern Hemisphere?

Clockwise

Which of the following would most likely occur in a region of surface divergence?

Sinking air

What is the key difference between gradient winds and geostrophic winds?

Gradient winds curve around highs and lows

What process causes katabatic winds to form?

Air descending due to cooling on elevated terrain

What describes a land breeze?

Occurs at night, from land to sea.

What causes the Coriolis effect?

Earth’s rotation.

What is the main characteristic of geostrophic wind?

It results from balance between Coriolis force and pressure gradient force.

What is the result of friction near Earth’s surface on wind speed?

Reduces wind speed.

What effect does surface friction have on wind direction?

Causes wind to cross isobars toward low pressure.

Where is the Coriolis effect strongest?

At the poles.

Why does a valley breeze blow uphill during the day?

Warm air rises along the slopes.

What causes pressure differences on Earth’s surface?

Uneven heating of Earth’s surface.

What happens to wind speed as you move higher in the atmosphere (above the friction layer)?

Increases.

In what layer of the atmosphere do jet streams occur?

Troposphere.

What direction do cyclones rotate in the Northern Hemisphere?

Counterclockwise.

What causes surface winds to be slower than winds aloft?

Greater friction at the surface.

Which of the following winds is a type of local wind?

Sea breeze.

Why do pressure gradients cause wind?

Air moves from high to low pressure.

When is a sea breeze most likely to occur?

During the day.

What happens to the direction of geostrophic wind when isobars curve around a high pressure system?

It becomes gradient wind.

Why does a land breeze form at night?

Land cools faster than water.

What kind of wind would you expect with strong pressure gradients?

Strong winds.

Which of the following is true about air in a high pressure system?

It descends and warms.

What local wind can bring sudden warming to areas east of the Rockies?

Chinook wind.

What is the primary motion of air in an anticyclone?

Sinking and spiraling outward.

What causes geostrophic wind to occur?

Balance between pressure gradient and Coriolis forces.

Which term best describes downward movement of cold air from elevated terrain?

Katabatic wind.

What is the typical direction of sea breeze movement during the day?

From sea to land.

How does friction affect the direction of wind near Earth’s surface?

Causes it to cross isobars at an angle.

Which force is responsible for deflecting moving air to the right in the Northern Hemisphere?

Coriolis effect.

What is the effect of air divergence aloft on surface pressure?

Lowers surface pressure.

What condition would likely result in calm and clear weather?

High pressure system.

What causes the formation of jet streams?

Strong pressure gradients in the upper atmosphere.

What kind of wind system dominates large-scale upper atmosphere circulation?

Geostrophic winds.