Weather Temporary behavior of atmosphere (what’s going on at any certain time) Small geographic area Can change rapidly
Weather --The study of weather is meteorology --Someone who studies weather is called a meteorologist
Climate Long-term behavior of atmosphere (100+ years) Large Large geographic area slow Very slow to change
Climate Zones The Earth’s climate can be divided into general climate zones according to average temperatures. The three major climate zones on the Earth are the polar, temperate, and tropical zones.
POLAR 90 o -60 o latitude Cool summers, cold year-round Dry
In each hemisphere, the polar zone extends from the pole to about 60 degrees latitude. In polar zones, the average yearly temperature is below freezing. There are some areas in the polar zones, such as the northern coasts of Canada and Alaska and the southern tip of South America, where the snow melts during the warmest part of the year. POLAR
TEMPERATE 60 o -30 o latitude True Seasons Variety of climate patterns Moderate precipitation (rain/snow)
In each hemisphere, the temperate zone is found between 60 degrees and 30 degrees latitude. In the areas of the temperate zones farther from the equator, snow is common in the winter. In the areas of the temperate zones closer to the equator, rain normally falls all year round. The average amount of precipitation is about the same throughout. The average temperatures range from 5 ° C to 20 ° C. TEMPERATE
TROPICAL 30 o - equator No winter, warm year-round High temp, rainfall, humidity
The tropical zones, which extend from 30 degrees north and south latitude to the equator, have high temperatures and high humidity. Tropical zones are also known as low- latitude climates. The average temperature during the coldest month of the year does not fall below 18 ° C. TROPICAL
Climate Elements These include temperature, humidity, precipitation, pressure and winds.
Climate Controls (PSALMON) Prevailing winds Slope or aspect of the land Altitude Latitude Mountain barriers Ocean currents Nearness to large bodies of water
Prevailing Winds More moisture is present in air blowing over the sea, and precipitation is likely if prevailing winds blow from water to land. The opposite effect occurs as air blows from land to sea. The air becomes warm and dry or cold and dry depending on the time of year.
Slope AKA Aspect The amount of solar radiation received on the earth’s surface will vary according to the slope or aspect of the land. For example, a north facing will receive less solar radiation than a south-facing slope in the northern hemisphere. That is why you often find moss growing on north facing roofs of houses.
Altitude Elevation, or altitude, is the distance above sea level. As elevation increases, the air becomes less dense. Less- dense air cannot hold as much heat as denser air. So the higher the altitude in the atmosphere, the lower the temperature. The climate on tops of mountains will vary from climates of valleys. Snow can be found on mountaintops near the equator because of the effect of altitude.
Latitude Latitude is the measure of the distance north and south of the equator. Latitude is measured in degrees. Areas close to the equator, or 0 degrees latitude, receive the direct rays of the sun. These direct rays provide the most radiant energy. Areas near the equator have a warm climate. Polar regions have a cold climate.
Mountain Barriers The amount of precipitation at a particular location is also affected by mountain ranges. A mountain range acts as a barrier to prevailing winds. The windward side of a mountain has a wet climate. On the leeward side, relatively dry air moves down the side of the mountain and results in very little precipitation. Chinooks are examples of mountain barrier affects on climate.
Ocean Currents Ocean currents affect the temperature of the land they pass by Cold ocean currents = cooling effect Warm ocean currents = warming effect Temperature changes affect pressure – which then creates WINDS Winds blow this cooling or warming effect over the land
Ocean Currents Some short-term changes may be the result of changes in ocean currents and global winds. Ocean currents help transfer heat to the atmosphere. This process generates global winds. The global winds help move ocean currents. Any major change in an ocean current can cause a change in climate. El Nino is an example.
Nearness to Water The climate of a region can be affected according to its proximity to large bodies of water. Water and land cool at different rates. Water retains more heat than does land in the winter months and this is the reason why Vancouver’s climate is mild and wet as compared to the prairie region where land tends to cool more quickly. During the summer months land heats up more quickly than does water. Regions located away from large bodies of water also experience greater temperature ranges.