Changes in the Atmosphere Earth Science Chapter 11.2 & 11.3

SIX Factors to Consider 1. Temperature 2. Humidity 3. Pressure 4. Wind 5. Precipitation 6. Clouds

What Happens to the Sun’s Rays? TOP OF ATMOSPHERE What’s the Point? IR Radiation reflected back by Earth? CO2 gases from combustion? TROPOSPHERE 4% Reflected by Earth’s Surface

What Happens to the Sun’s Rays? 6% Reflected by Atmosphere TOP OF ATMOSPHERE 15% absorbed by Atmosphere 25% reflected back by clouds TROPOSPHERE 4% Reflected by Earth’s Surface 50% of all rays ABSORBED by Earth Earth

Warm air can hold more water vapor compared to cold air!!!! Relative Humidity Humidity is the amount of water vapor in the air Relative humidity is the % of water vapor compared to what the air can hold Warm air can hold more water vapor compared to cold air!!!!

Air Pressure Pressure changes as the temperature changes: HOT AIR rises, putting less pressure on the ground COLD AIR sinks, adding more pressure to the ground Pressure also changes with altitude: pressure is low at high elevations, and vice versa

Effects of Pressure High Pressure pushes air away. Wind, clouds and rain go away as air leaves the high. Low Pressure is where the air ends up. The wind, clouds, and rain move toward the low. L H

WIND Wind is the horizontal movement of air from areas of high density and high pressure to areas of low density and low pressure. Unequal heating causes these differences. High density High pressure Low density Low pressure High density High pressure Low density Low pressure

Types of Precipitation Rain Snow Sleet Hail

Largest Hailstone in US History: 8” across, 18” around, 1.94 pounds

Three Requirements for Clouds to Form: 1. Moisture in the air 2. Temperature drops below the dew point 3. Condensation Nuclei

Temperature versus Heat Temperature is a measurement of how fast or slow molecules move http://www.indiana.edu/~oso/animations/energytransfer.html Temperature is measured in either Fahrenheit, Celsius or Kelvin Heat is the transfer of energy from a warmer substance to a cooler substance.

Air Temperature and Cloud Formation Condensation Nuclei – dust, pollen, salt or other small particles around which cloud droplets form Dew Point – temperature at which condensation occurs Condensation= water vapor turns into a liquid

Four Ways Clouds Form

Clouds form when air fronts of different temperatures collide Clouds form when air fronts of different temperatures collide. The warm air is forced up and cools, causing water vapor to condense… clouds form.

We also see how the terrain in Tahoe and Nevada is very different , due to Sea and Valley Breezes . . . Clouds get “stuck” upon the mountains and build up moisture. Clouds “vacuum” up more moisture as they warm up past the mountain ridge, creating a more arid climate.

Orographic Lifting – Warm moist air is forced up when the wind hits a mountain, then clouds form.

Temperature Inversions Normally air temperatures decrease with increasing altitude. Temperature inversions are an exception. This may occur when the land cools quickly on cold windless nights. The cool air is then trapped by warmer air above. Pollution can be trapped as well!

The Water Cycle

Types of Clouds Clouds are classified according to the height at which they form and their shape Height (prefix) Shape (prefix) and Latin meaning Cirro – high clouds Cirrus “hair” – wispy, stringy clouds Alto – middle clouds Cumulus “pile or heap” – puffy clouds Strato – low clouds Stratus “layer” – flat, blanket like clouds Nimbus “cloud” – low grey rain clouds