Lecture #6 (Atmosphere) Flashcards
What are the 4 different layers of the atmosphere?
Thermosphere (>85km); Mesosphere (50-85km); Stratosphere (10-50km); Troposphere (0-10km)
When UV interacts with ozone & other molecules what happens to the air density? Which leads to a(n) ____ in temperatures in the upper stratosphere
Air density starts to increase; increase
Which ozone layer is key?
Stratosphere
What is a jet stream?
A narrow (250-500 km wide; several km deep) band of strong horizontal winds in the atmosphere at altitudes of 30,000 to 40,000 ft. Winds in this band are stronger than those adjacent to it
What happens after air is heated in the tropics-equator?
The air gets sent up and towards the poles. In turn air in the poles move toward the equator, but due to a few reasons, including rotation of planet, there is an intermediate cell.
How does a subtropical jet stream form?
As a result of the principle of the conservation of angular momentum.
What is the conservation of angular momentum?
Air is heated and rises over the area with the strongest solar radiation (equator). At the top of the troposphere, this rising air moves toward the poles. As it moves toward the poles, the distance between it & the Earth’s axis decreases. As this distance decreases, the air accelerates toward the west. The air reaches its maximum westward velocity between 20’ & 40’ from the equator & then starts sinking
What are the 3 main “cells” in global circulation patterns?
- Hadley cell (Equator to 30’ N/S)
- Ferrel (mid-latitude) cell (30’ to 60’ N/S)
- Polar cell (60’ to 90’ N/S)
What is the Coriolis force?
Creates the patterns of winds in the cells (‘trade’ winds)
Rossby waves are also known as what?
Long waves
How do Rossby waves form?
Due to the earth’s geography:
1. Differential heating of Earth’s surface (heating from the sun is uneven due to the different shapes & sizes of land masses)
2. Major mountains deflect the jet stream since air can’t travel through a mountain so it must rise up & over or go around
What are short waves?
They’re embed within the long wave pattern forming smaller cycles or troughs such as a “pocket of cold air” moving down from polar areas in winter
How many general planetary waves are in the Rossby (long) wave pattern?
5
What is the El Nino-Southern Oscillation (ENSO)?
A quasi-periodic fluctuation in winter ocean temperatures in equatorial Pacific: warmer than normal central & eastern equatorial Pacific
El Nino has major effects on ______ weather conditions affecting ecosystems & species
trans-Pacific
El Nina is associated with ___ than normal central & eastern equatorial Pacific.
cooler
Easterly trade winds results in ___ upwelling in east
cold
Weakened east trade winds results in ___ upwelling in east
less
During a strong El Nino, how are Galapagos penguins effected?
The cycle slows or is shut down leading to a massive decline in penguins, since they rely on fish that rely themselves on phytoplankton
How does an El Nino effect North American weather?
Causes the Pacific jet stream to move south & spread further east. During winter it leads to wetter conditions than usual in the Southern US & warmer and drier conditions in the Northwestern side of the continent
How does an El Nina effect North American weather?
Causes the jet stream to move northward and to weaken over the eastern Pacific. During La Nina winters, the South sees warmer and drier conditions than usual. The North and Canada tend to be wetter and colder
What is the orographic effect (lift) of mountains?
When an air mass moves from low to high elevation (over mountains), and as the air mass gains altitude it cools adiabatically, increasing relative humidity (to 100%) & thus creates clouds or under the right conditions precipitation
What does orographic lifting affect?
Precipitation, rain shadowing, leeward winds, & associated cloud patterns
Define Adiabatic
The change in temperature caused by the expansion (cooling) or compression (warming) of a body of air as it rises or descends in the atmosphere, with no exchange of heat with the surrounding air