CH 8 Flashcards
Hadley cell
Near the equator, low atmospheric pressure.
Air in these cells rises near the equator because of strong solar heating there and falls because of cooling at about 30 degrees latitude.
Ferrel cell
Mid latitudes, high atmospheric pressure.
Polar cell
Near poles, high atmospheric pressure.
Meteorological Equator (ITCZ)
Near the equator where the trade winds of the northern and Southern Hemisphere collide.
- changes with seasons.
- ITCZ is farthest north in July and farthest sound in January.
Doldrums
Calm equatorial areas where two Hadley cells converge also known as the ITCZ( inter tropical convergence zone)
Horse latitudes
Between Hadley and ferrel cells, high atmospheric pressure and little surface winds.
Trade winds & Westerlies
Trade winds: surface winds of Hadley cells, also known as easterlies.
Westerlies: Surface winds of ferrel cells
Air masses & Fronts
A large mass of air with nearly uniform temperature, humidity, and density throughout.
Fronts:the boundary between two air masses of different density. The density difference can be caused by differences in temp. Or humidity.
In what layer does most weather occur on Earth?
Troposphere
Know the top 2 components in our atmosphere.
Nitrogen & oxygen
Know how water vapor affects the density of dry air.
Temperature and water content
What happens to an air parcel as it is forced to rise or sink?
In order for clouds to form, air parcels must rise high enough for their temperatures to cool down to the dew point temperature, when saturation (100% relative humidity) occurs. Rising air takes place when it is warmer than the surrounding environment, or when forced to rise by mountains or a front.
What causes summers and winters?
The earths tilt of 23.5 degrees
Know the fundamentals behind a sea and land breeze.
Sea breeze: onshore movement of air as as inland air heats and rises.
Land breeze: movement of air offshore as marine air heats and rises.
What is and what creates a monsoon?
A pattern of wind circulation that changes with the season. Also, the rainy season in areas with monsoon wind patterns.
What is a “rain shadow”?
A rain shadow is a dry area on the leeward side of a mountainous area. The mountains block the passage of rain-producing weather systems and cast a “shadow” of dryness behind them.
What is meant by windward and leeward?
The leeward side is the drier side or the side where the trade winds pass after they hit a mountain. The windward side is the wetter side.
How do winds generally move at different latitudes?
6
Where(what latitudes) on the planet would you find areas of very little surface wind motion but a lot of vertical air motion?
7
At what latitudes would you find deserts, why?
30 degrees latitude south and north where the air descends
At what latitudes would you find rainy conditions, why?
This tropical rain belt runs along the equator and spreads out to about the Tropic of Cancer (23.5 north latitude) and Tropic of Capricorn (23.5 south latitude).
What is the coriolis effect caused by?
The apparent deflection of a moving object from its initial course when its speed and direction are measured in reference to the surface of the rotating earth.
How are the winds steered in the northern and Southern Hemispheres?
2
In what direction do winds rotate around a low and high pressure in the northern and Southern Hemispheres?
3
Know how tropical storms rotate and what direction they typically travel.
In the Southern Hemisphere, winds traveling toward the equator will move eastward, and winds traveling toward the South Pole will curve west. When these winds collide, they will swirl clockwise in the south, and counterclockwise in the north.
How do winds move in the center of the storm?
Because of Earth’s spin and the Coriolis Effect, winds of a low pressure system swirl counterclockwise north of the equator and clockwise south of the equator. This is called cyclonic flow. … A high pressure system has higher pressure at its center than the areas around it. Wind blows away from high pressure.
Know the energy source for tropical storms/hurricanes.
How do hurricanes form? Tropical cyclones develop when low-pressure systems gather heat and energy as they absorb warm ocean water near the equator. Evaporation from the ocean surface fuels them like giant heat engines, creating powerful winds twisting around a relatively peaceful center, called the “eye.”
What is usually the minimum temperature for hurricane formation?
26.5 degrees Celsius 80 degrees Fahrenheit
Why don’t hurricanes form on the equator?
Observations show that no hurricanes form within 5 degrees latitude of the equator. People argue that the Coriolis force is too weak there to get air to rotate around a low pressure rather than flow from high to low pressure, which it does initially. If you can’t get the air to rotate you can’t get a storm.
