ENVS 224 - HW 4 - Homework #4

Homework – #4

1) Describe the conditions in the Pacific Ocean region during an El Niño event. Use this link for help. Grab one image from this link and post in this document. http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/ensocycle/enso_cycle.shtml

During an El Niño, the trade winds weaken in the central and western Pacific. Surface water temperatures of South America warm up, because there is less upwelling of the cold water from below to cool the surface. The clouds and rainstorms associated with warm ocean waters also shift toward the east.

2) Consider the typical mid-latitude low pressure system with its weather fronts that is located in the eastern United States. Describe the wind flow around this system and how the wind rotation around the pressure center moves various air masses northward and southward. How do these weather systems help to keep Earth's climate stable? http://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php Grab one map from this link and post in this document.

The flow of wind flows counterclockwise around the low northern hemisphere. The opposite is valid on the southern hemisphere. There is where the wind flows clockwise around an area of low pressure.

3) Have humans already caused a detectable increase in Atlantic hurricane activity or global tropical cyclone activity? You can use this link for help: https://www.gfdl.noaa.gov/global-warming-andhurricanes/

1) Atlantic hurricane and tropical storms are substantially reduced in number, for the average 21st century climate change projected by current models, but have higher rainfall rates, particularly near the storm center.

2) It is likely that greenhouse warming will cause hurricanes in the coming century to be more intense globally and have higher rates than present day hurricanes.

3) Hurricane model projects that the lifetime maximum intensity of Atlantic hurricanes will increase by about 5% during the 21st century.

4) There is little evidence from current dynamical models that 21st century climate warming will lead to large (`300%) increases in tropical storm numbers, hurricane numbers, or PDI in the Atlantic.

5) Detection of an anthropogenic influence on intense hurricanes would not be expected for a number of decades even assuming a large underlying increasing trend (+10% per decade) occurs.

4) What changes in hurricane activity are expected for the late 21st century, given the pronounced global warming scenarios from current IPCC models? USE ABOVE LINK FOR HELP.

The large increases in tropical Atlantic SSTs projected for the late 21st century would imply very substantial increases in hurricane destructive potential-roughly a 300% increase in PDI by 2100. Also, there is projections that hurricane activity continue to support the notion of increased intensity (~4%) and near-storm rainfall rates (~10-15%) for the Atlantic basin as well as for most other tropical cyclone basins found model-projected increases in rainfall rates for US landfalling tropical cyclones using this modeling system.

1) Section 4.9 Describe two of the three ingredients needed for hurricanes and other tropical cyclones to develop.

A) Increased warming of the upper troposphere relative to the surface

B) Increase vertical wind shear

2) Section 4.10 Describe the mechanics of a tropical monsoon. Be sure to include heating, pressure, vertical motion, and precipitation. Which two regions of the world are known for their monsoons?

Areas of deep atmospheric convection and precipitation that occur outside of the equator. They develop over land surfaces during the summer season when heating from the sun is the most intense. The surface of land warms in the summer, tropical monsoons transfers energy to the atmospheric boundary layer. The action of convection then creates low pressure at the surface and brings humid air from the surrounding ocean.

Regions: India, South Asia and Australia

A

B

3) Refer to figures A and B. Explain how the annual changes in the ITCZ (inter-tropical convergence zone) cause the Amazon to be a tropical rainforest climate (wet all year) while India's climate is a classic monsoon (wet vs. dry).

Annual changes in the ITCZ causes the Amazon to be tropical and India to have monsoons is caused by the average position of the polar front in the northern hemisphere. The separations between cold dry polar air and mild and moist temperate. In the summer, it shrinks to perhaps 70 N and in the summer goes down to 50 N. Similarly, the intertropical convergence zones will move north and south of the equator. This follows the seasons.

4) During La Niña events, global average temperatures:

A) Increase

B) Decrease

C) Increase during part of the year and decrease during the other

D) Are unaffected

5 ) El Niño events are characterized by:

A) Cool water flowing westward

B) Warm water flowing westward

C) Cool water flowing eastward

D) Warm water flowing eastward

6) The African Monsoon occurs when: (sec 4.10) A) The Eastern Atlantic Ocean warms during summer.

B) The Western Indian Ocean warms during summer.

C) The ITCZ shifts northward during summer.

D) The ITCZ shifts southward during summer.

7) The impact of climate change on tropical cyclones is expected to:

A) Make them wetter

B) Make them more intense

C) Decrease the number of storms

D) All of the above