Climate and Weather

How are weather and climate different? Weather Vs. Climate Weather is the condition of the atmosphere at a given time and place. Weather conditions in a geographic region over a long time period are called climate.

4 Factors or Elements that Affect Climate: Latitude Wind Currents Proximity to Water Elevation

#1 Latitude: Latitude can affect climate through circulation. Different latitudes have different climate zones.

Temperate Tropics Tropics Temperate Polar Polar 66.5 degree N to North Pole Polar Temperate Tropics – high temperatures are the norm. Temperate zones, have evident seasons. Tropics Tropics Temperate Polar 66.5 degree S to South Pole

Climate Zones: Low Latitudes Tropical Humid Climate: Areas closer to the equator Warm temperatures, plentiful rainfall Never truly have cold weather Tropical Wet/Dry Climate: Tropical Savanna Climate Results in seasonal change Tropical grassland, scattered trees, and shrubs Arid Climate: 30 degrees North and South of the Equator. Dryness caused by subtropical high pressure zones. Little rainfall. Found in rain shadows. Semi-arid Climate: Transition zone between arid climate and the more humid climate. Receives more moisture than a desert, but less than the more humid areas.

Climate Zones: Middle Latitude Mediterranean Climate: Exists mainly in two kinds of areas Along coastal areas of South Europe West of continents with cool ocean currents Humid Subtropical: More wide spread, found on the Eastern side of continents where there are warm ocean currents. Summers are hot and winters are mild. Marine West Coast: Heavily influenced by the oceans Found on the west coast of continents in the upper middle latitudes. Mild all year Humid Continental Climate: Found in the interiors and east coasts of the upper middle latitude continents. Warm and cold air regularly affect these areas. Most changeable weather conditions. 4 distinct seasons

Climate Zones: High Latitude/Highland Subarctic: Located 50 degrees North latitude Warm ocean currents moderate the climate in areas above this latitude in Northern Europe. Long cold winters Temperature below freezing at least half of the year. Ice Cap Climate: Found in the Earth’s polar region Covered by huge flat masses of ice and snow Antarctica and Greenland Highland Climate: Have varying climates Temperature changes with elevation Prevailing wind patterns affect rainfall on the windward and leeward sides of the highland areas. Tundra: Coastal areas in high latitudes have this climate Temperature is above freezing during short summers

#2: Wind Currents Air pressure affects global wind patterns. Wind is the horizontal flow of air. Wind moves heat and cold across the earth’s surface, which helps maintain global energy balance.

Air Pressure and Wind Air is a fluid Warmer air is less dense Air moves from dense to less dense conditions Ex.: Land-sea breezes Air Pressure

Air Pressure Warmer air “holds” more water Low pressure=warm air=precipitation High pressure=cold air=dry air

Prevailing Winds These are areas of the world that have winds that blow from the same direction most of the time. Trade winds: prevailing pattern of easterly surface winds found in the tropics, within the lower portion of the Earth's atmosphere, in the lower section of the troposphere near the Earth's equator. Westerlies: from the west toward the east in the middle latitudes between 30 and 60 degrees latitude. They originate from the high-pressure areas in the horse latitudes and tend towards the poles and steer extratropical cyclones in this general manner. Polar Easterlies: the dry, cold prevailing winds that blow from the high-pressure areas of the polar highs at the north and south poles towards low-pressure areas within the Westerlies at high latitudes.

Weather Fronts: These occur when two air masses of widely different temperature or moisture levels meet. Precipitation often occurs along these fronts

#3 Proximity to Water: Water heats and cools more slowly than land. Land areas near the oceans have a milder winter and a cooler summer. ocean currents and climate

Ocean Currents: Move heat back and forth between the tropics and the polar regions. Warm water flows away from the equator and cold water flows toward the equator. This movement helps to maintain Earth’s energy balance.

Ocean Currents: Follow same circular pattern (driven by wind) Warm currents flow away from equator, pile up on eastern shores ex. Gulf Stream Cold currents flow towards equator, cause upwelling

#4 Elevation: Elevation affects weather and climate. The increase in elevation (height on Earth’s surface above sea level) causes a drop in temperature. Temperature drops 3.5 degrees per 1,000 feet in elevation. As you go up in elevation the temperature becomes colder because the atmosphere is thinner. Areas with very high elevations can have vegetation similar to the arctic.

Orographic Effect and the Rain Shadow Ms. Frizzle explains…

Elevation: Mountain’s influence climate through orographic effect. This occurs when moist air pushes against a mountain. The barrier forces the air to rise. The rising air cools and condenses, forming clouds and causing precipitation.

Elevation: Rain Shadow Effect: The side of the mountain facing the wind receives a great deal of moisture. The side of the mountain facing away from the wind is the Leeward side. As air moves down this side of the it warms and dries. Drier air = Rain Shadow Deserts are often located in the rain shadow.