WEATHER & CLIMATE Investigative Science

WEATHER VS. CLIMATE  Climate determines what clothes you buy.  Weather determines what clothes you wear.  Climate is: the long-term average of variation in weather for a particular area.  Weather is: short-term variations in atmospheric phenomena that interact and affect the environment and life on Earth

FACTORS INFLUENCING WEATHER  Some factors that influence weather in a particular area are:  Air pressure  Humidity  Temperature  Clouds

AIR PRESSURE  Air pressure is the pressure exerted on a surface by the weight of the atmosphere above it.  Density of air: Near sea level, the density of air is the greatest and the pressure exerted by the air is the greatest. Why?  What happens to air pressure as you go up a mountain? Or move higher away from Earth?

DENSITY OF AIR  In the atmosphere, the temperature, pressure and density of air are related to each other.  Increased temperature means the particles of air are colliding more often and with greater force---this leads to ↑ air pressure.  Decreased temperature means the particles of air are not hitting each other as often—this leads to ↓ air pressure.

HUMIDITY  Humidity is the amount of water vapor in the atmosphere at a given location on Earth’s surface.  The distribution and movement of water vapor in the atmosphere plays and important role in the weather.  As water evaporates into the air, it rises and when it reaches the upper part of the Troposphere, it cools and condenses into clouds.

RELATIVE HUMIDITY  Relative humidity is the amount of water vapor in a certain volume of air compared to how much water vapor that air could possibly hold. Warm air can hold more water vapor.

CLOUDS  Clouds form when a rising air mass cools. Remember: the Troposphere cools as you get further away from Earth!  Water vapor in the atmosphere cools and condenses to form water droplets.  Water droplets form around condensation nuclei (small particles of dust, ice, salt or other materials).

CLOUD FORMATION