Weather & Climate Objectives: 1) Sun’s affects 2) Understand atmospheric pressure 3) Global wind belts affect weather/climate 4) Oceans affect on weather/climate

Opening Activity 1) What would happen if, for one week, all the winds in the world were still? Define Terms on page 41 Possible Answers: Temperature differences would become extreme air pollution would get worse ocean waves would calm

What is what? Weather is the condition of the atmosphere at a given time and place Weather conditions in a geographic region over a long time are called climate.

The Sun Solar Energy Greenhouse effect Global Warming ½ reflected back in space/atmosphere ½ absorbed and converted to heat = temperature Greenhouse effect Trapped heat Global Warming Increased carbon emissions Debate continues

Atmospheric Pressure Atmosphere has weight Called atmospheric pressure or air pressure As elevation increases air pressure decreases Airplanes Mountain climbers Low pressure: hot air rises, cool and forms clouds Cyclones Unstable weather High pressure: cold air sinks to earth, heats up Clear skies Extreme heat or cold

Four Air Pressure Zones The Four Equatorial Low Subtropical Highs Subpolar Lows Polar Highs Carry air back and forth from equator to Poles From equator – warm air rises, then cools and sinks as it nears Poles

Wind Belts Air pressure affects wind patterns. Wind is the horizontal flow of air, moving from low to high pressure areas moving cold or hot air Wind moves hot and cold air across earth’s surface Types of winds Prevailing winds Westerlies, Easterlies Jet Stream, Upper atmosphere Doldrums Between tropics Fronts Two air masses meet

Jet Stream During WWII, Japan used the jet stream that flows across the Pacific to North America to deliver bombs Called Fu-go, which means “wind ship weapon” As far as Michigan Today pilots use jet stream to save fuel and time.

On your own Locate the following locations on page S23, and identify the types of winds likely to be found in each of these areas: Greenland New York, New York The Galapagos Islands Tasmania Outer edges of Antarctica Answers: Greenland and Antartica – cold polar easterlies; New York City and Tasmania – Westerlies; Galapagos Islands – no prevailing winds

Oceans and Currents Oceans affect climate Land near oceans do not have great temp ranges San Fran. vs. Kansas City Currents move heat back and forth between Tropics and Polar Regions Maintains Earth’s energy balance Gulf Stream Warm current Effect of Europe

Closing Thought During the 1700’s sailors dubbed the northern edge of the northeast trade winds belt the horse latitudes. Ships caught in the region would often run low on supplies. To save water, the horses would be thrown overboard so the people could survive.

Precipitation Elevation Storms Weather Factors Precipitation Elevation Storms

Precipitation Evaporation = process by which water changes from liquid to gas. Most water vapor that becomes rain comes from oceans Humidity = amount of water vapor in the air The higher the temp. the more water vapor the air can hold When air cools it will not be able to hold water vapor. At this point condensation occurs Condensation = water vapor changing from gas to liquid Appears as clouds, dew, fog, and mist

Forms of Precipitation Four common forms of precipitation are rain, snow, sleet, and hail

Precipitation varies around the world Precipitation varies around the world. Generally highest in low-pressure zones. These zones generally in the middle latitudes

Elevation Effects Increase in elevation causes a drop in temperature. Temp. drops 3.5 F per 1,000 feet of elevation. May be warm at the base of the mountain with snow covered peak.

Mountain Effects Orographic Effect – moist air pushes against a mountain. Rising air cools and condenses, forming clouds and precipitation Side of mountain facing wind receives great deal of moisture (windward side) Side facing away is leeward side As air moves down leeward side it warms and dries This drier air is called a rain shadow Deserts are often located

Storms Storms are sudden and violent weather events Most middle latitude storms occur along a polar front – form when cold dry polar air mixes with warm air from tropics Move from west to east Middle-latitude storms may produce tornadoes. The USA has most tornadoes

Storms Storms in the tropics differ from middle latitudes No cold air present, lack fronts Move westward with trade winds Hurricanes – violent tropical storms Begin over warm tropical seas Weaken as they move inland Winds up to 155 mph Typhoons: Hurricanes in the W. Pacific Ocean, can create dangerously high waves