What are the factors which affect the Uk climate?

Latitude Seasons (Sliding of the tri cell model) Seasons (Global position) Sea Direction of winds Ocean currents Altitude

UK Climate – Wind

UK Climate Rainfall

UK Climate – Temp (Summer)

UK Climate – Temp (Winter)

The Rain Making Process THE PRECIPITATION LADDER 11. PRECIPITATION 10. DROPLET GROWTH 9. BUOYANCY/CLOUDINESS 8. CONDENSATION 7. SATURATION 6. HUMIDIFICATION 5. COOLING 4. EXPANSION 3. ASCENT 2. DIRTY AIR 1. WATER VAPOUR

Simplified To rain we need….. Moisture in the air Air must rise (in order to cool) Air must be dirty (microscopic nuclei) Q – Why does it not rain much in the Sahara? Q – What happens if air cools but does not rise?

Convective Rainfall Heating from the sun warms the land, to cause lifting. As the air rises, it cools and condenses to form clouds. If the clouds grown in sufficient height, it rains.

Relief / Orographic Rainfall As the air comes ashore, it is forced to lift, causing it to cool and condense. As it condenses, clouds form to produce rain. Lea side of the mountain has very little rain, since it has been dropped already – producing the rain shadow.

Frontal Rainfall A cold wedge of air acts like a mountain, causing the lighter warmer air to rise. As the air rises it cools, condenses and clouds form to produce rain.

Rainfall Summary Convective rainfall occurs in warm places, especially in the afternoon (after the max heating). Orographic rainfall is common in mountainous and coastal locations where the air is forced to rise. Frontal rainfall is caused be the meeting of two air masses, which creates a ‘front’ which separates warm and cool air – forcing the air to lift.

Major Step Whatever the process causing an air parcel to ascend, the result is that the rising air parcel must change its pressure to be in equilibrium with the surrounding air. Since atmospheric pressure decreases with altitude, so too must the pressure of the ascending air parcel. As air ascends, it expands. And as it expands, it cools. The higher the parcel rises, the cooler it becomes.

Extra detail When rain falls, we know from measurements that the drops are larger than one millimetre. A raindrop of diameter 2 mm contains the water equivalent of a million cloud droplets (0.02 mm diameter). So if we are to get some precipitation from a cloud, there must be additional process within the cloud to form raindrops from cloud droplets

Extra detail Buoyancy or Cloudiness which signifies that we must increase the cloud water content before we can expect any precipitation. This requires a continuation of the lifting process. It is assisted by the property of water of giving off heat when changing from vapour to liquid (LATENT HEAT). (If the vapour first changes to a liquid before freezing, then we also have the latent heat of condensation released and followed by the release of the latent heat of freezing.) This additional heat release warms the air parcel. In doing so, the buoyancy of the parcel relative to the surrounding air increases, and this contributes to the parcel's further rise.

Extra Detail Extra growth must occur to droplets to be big enough to avoid re-evaporating on the way back to earth. Continued condensation, collision of droplets, or formation of ice crystals all growth of each droplet

Describe the link between latitude and Rainfall

Homework Read over p62-65