Ch. 13 Section 1

Objective Compare and contrast weather and climate. List and describe factors that influence them and analyze their impact.

Weather Is the state of the atmosphere at a particular place at a particular moment.

Climate Is the long term prevailing weather conditions at a particular place based upon records taken.

New York vs Aiken Two cities may experience the same weather, but their climate is different. Gets below zero Aiken 2/12/2010

What factors determine climate? 1. Latitude 2. Atmospheric circulation patterns 3. Oceanic circulation patterns 4. Geography 5. Solar activity 6. Volcanic activity

1. Latitude The distance from the equator measured in degrees north or south. The most northerly latitude would be the North pole at 90 degrees North.

LATITUDES Low latitudes High latitudes On either side of the equator. More solar energy falls here. Sun is concentrated on smaller surface area. Night and day are about 12 hours each. Temperatures are high year round. Closer to the poles. Sun is at oblique angle and spreads over larger surface area. Day and night vary more. Temperature range is greater.

Lattitudes

DNC Equator markers

DNC- Brasilia Brazil Climate is Tropical savanna climate. The individual seasons are defined according to the degree of humidity of the air: one season is dry, while the other one is comparatively humid. September, at the end of the dry season, has the highest average maxi temp,82 °F, and July has the lowest average max temp, 77 °F. The lowest average minimum temperature is in July 55 °F.

DNC Siberia The by far most common climate in Siberia is continental subarctic, with the annual average temperature about 23 °F and roughly −13 °F average in January and 62.6 °F in July. there is a very short (about one-month-long) summer

2. Atmospheric Circulation Large scale movement of air. As cold air sinks it compresses and warms. As warm air rises it expands and cools. Warm air holds more water vapor than cool air so as it cools the vapor may condense into rain, snow or fog. The movement of air is called wind.

2. Atmospheric circulation cont Due to the amount of sun the areas around the equator receive there is a lot of evaporation. Remember the warm air will rise and cool. Areas around the equator tend to have large amounts of rain.

Prevailing winds Movement of air causes wind. Winds that blow predominantly in one direction are prevailing winds. Trade winds are belts of prevailing winds. Northern Hemisphere blow from NE Southern Hemisphere blow from SE Examples of prevailing winds are westerlies and polar easterlies.

Global Air Circulation

3. Ocean Circulation Patterns El Nino Southern Oscillation (ENSO) El Nino- short term (16-18 month period) Periodic Change in the warm and cold water masses in Pacific Ocean. El Nino and La Nina are opposite phases of ENSO cycle. El Nino-warm phase, La Nina- cold phase.

Oceanic Circulation Patterns Cont. Pacific Decadal Oscillation Long term change (20-30 years) Affects Ocean surface temperatures, air temperatures and precipitation patterns

4. Geographic-Topography Rain shadow Mountains influence the distribution of precipitation. As air rises up the mountain it cools and rains. When it reaches the other side of the mountain it is dry.

Rain Shadow

4. Geographic-Topography

Solar activity At a solar maximum, the sun emits an increased amount of ultraviolet (UV) radiation. UV radiation produces more ozone, which warms the stratosphere. The increased solar radiation can also warm the lower atmosphere and surface of Earth a little.

6.Volcanic Eruptions Releases sulfur dioxide into air. Stays in atmosphere up to 3 years. Reacts and forms layer of haze that deflects sunlight and reduces global temperature.

He is standing on a road. Glaciers flood when they melt

Seasonal Changes in Climate The seasons result from the tilt of Earth’s axis, which is about 23.5° relative to the plane of its orbit. Because of this tilt the angle at which the sun’s rays strike Earth changes as Earth moves around the sun.

Seasonal Changes in Climate

During summer in the Northern Hemisphere, the Northern Hemisphere tilts toward the sun and receives direct sunlight. Therefore, the amount of time available for the sun to warm Earth becomes greater. During summer in the Southern Hemisphere tilts away from the sun and receives less direct sunlight. But, during the summer in the Southern Hemisphere, the situation is reversed.